CA^ 


< 
a 


A   MANUAL 


OP 


HYGIENE  AND  SANITATION 


BY 


SENECA  EGBERT,  A.M.,  M.D. 

PHOFESSOR  OF   HYGIENE,    UNIVERSITY   OF    PENNSYLVANIA,    FORMERLY    PROFEHHOR 

OF    HYGIENE,  AND  DEAN  OF  THE    MEDICO-CHIRURGICAL    COLLEGE;    SOMETIMK 

MAJOR,  MEDICAL  CORPS,  U.  8.  ARMY;  MEMBER  OF  THE  AMERICAN 

MEDICAL  ASSOCIATION,  AMERICAN  PUBLIC  HEALTH 

ASSOCIATION,  ETC. 


SEVENTH  EDITION,  ENLARGED  AND  THOROUGHLY 
REVISED 


ILLUSTRATED  WITH   160  ENGRAVINGS  AND  5  PLATES 


LEA    &    FEBIGEK 

PHILADELPHIA   AND   NEW    YORK 
1919 


Copyright 

LEA  &  FEBIGER 

1919 


TO  THE 

MEMORY  OF  MY  FATHER, 

TO  WHOM  I  OWE  SO  MUCH)   TO  WHOM  I  COULD  REPAY  SO  LITTLE. 

THIS   VOLUME 

IS     MOST     AFFECTIONATELY 

DEDICATED. 


42453G 


PREFACE  TO  SEVENTH  EDITION, 


Recent  years  have  far  eclipsed  any  equivalent  periofl 
in  the  history  of  Hygiene  and  Sanitation,  both  in  the 
practical  application  and  in  new  developments  of  the 
principles.  This  advance  is  not  only  because  of  the 
intensive  and  universal  use  of  the  science  by  the  armies 
in  the  great  war,  but  also  because,  as  was  presaged  in  the 
two  preceding  editions,  public  health  measures  as  factors 
in  the  common  welfare  and  betterment  of  the  people  are 
being  more  widely  apprehended  and  appreciated  every- ^ 
where  and  measures  insuring  the  improvement  of  the 
health  of  many  are  already  completed  or  are  in  prospect 
of  early  achievement. 

Hence  the  revision  for  the  present  edition  has  been 
thorough  and  every  chapter  has  been  carefully  gone  over 
in  order  that  its  contents  might  be  fairly  abreast  of  the 
times.  Perhaps  it  may  seem  to  some  that  the  author  has 
been  too  conservative  in  retaining  much  of  the  old  and  in 
omitting  some  of  the  newer  matters  that  have  claimed 
attention  of  late,  but  it  should  be  remembered  that  this  is 
primarily  a  manual  of  fundamental  principles  ami  that 
mere  novelty  is  not  a  sufficient  warrant  for  giving  space 
to  what  is  not  as  yet  well  established  by  thorough  trial 
and  test.  Nevertheless  all  advisable  pruning  has  lx»en 
done  and  considerable  new  matter  has  been  added  in  the 


VI  PREFACE 

endeavor  to  bring  the  book  up-to-date  and  worthy  of  a 
continuance  of  the  kindly  reception  it  has  had  in  the  past. 

Especial  attention  has  been  given  to  the  chapters  on 
Sewage  Disposal,  Industrial  Hygiene  and  Military 
Hygiene,  because  each  of  these  subjects  is  now  one  of 
increased  importance  and  in  an  era  of  marked  advance. 
The  first  of  them  is  developing  rapidly  on  account  of  the 
growing  realization  of  its  influence  upon  the  health  and 
comfort  of  communities,  both  large  and  small.  Moreover, 
the  newer  developments  in  the  biologic  treatment  of  sew- 
age promise  much  and  are  leading  to  a  more  practical 
solution  of  the  general  problem. 

The  hygiene  of  industry  and  the  occupations  is  con- 
stantly enlarging  in  scope  and  growing  in  interest  and 
the  inevitable  and  extensive  expansion  of  industrial 
enterprises  subsequent  to  the  war  compels  attention  to 
it  as  one  of  the  most  important  branches  of  the  science 
of  public  health.  Likewise  the  part  that  Military 
Hygiene  has  played  throughout  the  recent  great  conflict 
and  the  benefits  that  it  has  given  to  all  the  nations  con- 
cerned, make  its  principles  and  its  new  development 
still  of  lively  interest  to  every  student  of  the  same  science. 
Hence  the  author  has  in  his  revision  given  special  consider- 
ation to  the  chapters  on  these  subjects  without  neglecting 
the  others  wherein  the  points  treated  are,  perhaps,  more 
stabilized. 

Knowing  how  fair  and  generous  its  former  readers  and 
critics  have  been,  the  author  is  once  more  emboldened  to 
send  out  the  volume  in  its  new  dress,  trusting  that  it  may 
still  be  of  value  in  meeting  the  needs  for  which  it  was 
planned.  S.  E. 

Philadelphia,  1919. 


CONTENTS, 


CHAPTER  I. 
Introduction 17 

CHAPTER  II. 
Bacteriology  and  Parasitology 36 

CHAPTER  III. 
The  Atmosphere — Air 69 

CHAPTER   IV. 
Ventilation  and  Heating 101 

CHAPTER  V. 
Water 146 

CHAPTER  VI. 
Food 229 

CHAPTER  VII. 
Stimulants  and  Beverages 277 

CHAPTER  VIII. 
Personal  Hygiene 285 

CHAPTER  IX. 
School  Hygiene 314 


viii  CONTENTS 

CHAPTP]R   X. 
Disinfection 338 

CHAPTER  XI. 
Quarantine        370 

CHAPTER  XII. 
The  Removal  and  Disposal  of  Sewage        .      .      .      .      .     389 

CHAPTER  XIII. 
Industrial  Hygiene  and  Occupational  Diseases  .      .      .     439 

CHAPTER   XIV.                   ^ 
Military  Hygiene 455 

CHAPTER  XV. 
Vital  Statistics 494 

CHAPTER  XVI. 

The  Examination  of  Air,  Water,  and  Food     ....     509 


HYGIENE  AND  SANITATION. 


CHAPTER  I. 
INTRODUCTION. 

Hygiene  may  be  defined  as  the  art  and  science  that 
considers  the  preservation,  promotion,  and  improvement 
of  health  and  the  prevention  of  disease.  It  treats  of 
the  laws  of  health  in  the  broadest  sense,  and  under  the 
general  term  may  be  included  a  number  of  subdivisions. 
Thus,  while  Personal  and  Domestic  Hygiene  are  resp)ec- 
tively  more  closely  related  to  the  affairs  of  the  individual 
and  the  household.  Sanitary  Science  also  finds  larger  fields 
and  broader  application  in  the  domain  of  Public  Health 
and  State  Medicine,  in  the  Hygiene  of  ]\Iunicipalities  and 
of  Occupations,  and  in  that  which  especially  relates  to 
the  physical  welfare  of  armies,  navies  and  other  large  and 
particular  groups  of  men. 

A  little  thought  will  show  that  under  the  general  head 
we  may  consider  the  preservation  and  promotion  of 
health;  practical  disinfection  and  the  means  of  avoiding 
preventable  diseases;  adaptation  of  diet  and  other  factors 
to  the  prevention  and  cure  of  perversions  of  nutrition; 
improvement  of  environment;  advances  in  sanitation 
and  industrial  hygiene,  etc.  Under  one  or  another  of 
these  themes  will  fall  the  discussion  of  the  air  we  breathe, 
the  water  we  drink,  the  food  we  eat,  the  soils  and  sur- 
roundings of  our  dwellings  and  communities;  and  at 
the  same  time  the  study  of  the  means  of  recognizing, 
avoiding,  correcting,  or  removing  all  detrimental  factors 
affecting  any  of  these.    In  addition,  there  must  be  the 

.      2  (17) 


18  INTRODUCTION 

study  of  climate  and  meteorology;  of  clothing  and  shelter; 
of  the  care  of  the  sick,  not  only  for  their  own  sake,  but 
that  they  may  not  endanger  the  well;  the  dangers  of  the 
abuse  of  stimulants,  narcotics,  etc.;  the  factors  initiating 
and  governing  epidemics,  and  the  desirability  of  chaste 

_  and  temperate  living,  exercise,  rest,  etc. 

Parkes  says  that,  "taking  the  word  'hygiene'  in  its 
largest  sense,  it  signifies  rules  for  the  perfect  culture  of 
mind  and  body.  It  is  impossible  to  dissociate  the  two. 
The  body  is  affected  by  every  mental  or  moral  action; 
the  mind  is  profoundly  influenced  by  bodily  conditions. 
(So  is  the  moral  conduct  of  individuals  or  communities.) 
For  a  perfect  system  of  hygiene  we  must  train  the  body, 
the  intellect,  and  the  moral  faculties  in  a  perfect  and  bal- 
anced order."  Again,  he  says;  "Looking  only  to  the 
part  of  hygiene  which  concerns  the  physician,  a  perfect 
system  of  rules  of  health  would  be  best  arranged  in  an 
orderly  series  of  this  kind.  The  rules  would  commence 
with  the  regulation  of  the  mother's  health  while  bearing 
her  child,  so  that  the  growth  of  the  new  being  would  be 
as  perfect  as  possible.  Then,  after  birth,  the  rules  (dif- 
ferent for  each  sex  at  certain  times)  would  embrace  three 
epochs:  of  growth  (including  infancy  and  youth);  of 
maturity,  when  for  many  years  the  body  remains  appar- 
ently stationary;  of  decay,  when,  without  actual  disease, 
though  doubtless  in  consequence  of  some  chemical  changes, 
molecular  feebleness  commences  in  some  part  or  other, 
forerunning  general  decay  and  death.  In  these  several 
epochs  of  his  life  the  human  being  would  have  to  be  con- 
sidered: First,  in  relation  to  the  natural  conditions  which 
surround  him,  and  which  are  essential  for  life,  such  as  the 
air  he  breathes,  the  water  he  drinks,  etc. ;  in  fact,  in  rela- 
tion to  nature  at  large.  Second,  in  his  social  and  corporate 
relations,  as  a  member  of  a  community  with  certain  cus- 
toms, trades,  etc.;  subjected  to  social  and  political  influ- 
ences, sexual  relations,  etc.  Third,  in  his  capacity  as  an 
independent    being,    having    within    himself    sources    of 

action  in  thoughts,  feelings,  desires,  personal  habits,  all 


SCOPE  OF  THE  SCIENCE  19 

of  which  affect  health  and  which  require  self-regulation 
and  control.  Even  now,  incomplete  as  hygiene  is,  such  a 
work  would,  if  followed,  almost  change  the  face  of  the  world .'  * 

The  preceding  paragraph  indicates  the  individual  or 
personal  aspect  that  marked  the  common  concept 
of  the  subject  until  a  comparatively  short  time  ago. 
More  recently  the  tendency  is  also  to  view  its  func- 
tions, opportunities  and  problems  from  a  social  and 
altruistic  stand-point,  and  the  field  has  so  enlarged 
in  this  direction  that  it  is  questionable  whether  it  may 
not  be  better  to  supplant  the  older  word — Hygiene — 
when  used  to  refer  to  the  general  science,  with  the  newer 
term — Public  Health  and  Preventive  Medicine.  But, 
after  all,  he  who  works  to  improve  the  sanitary  condition 
of  his  neighbors  and  his  neighborhood,  no  matter  how 
extensive  these  may  be  in  numbers  and  area,  at  the  same 
time  well  serves  his  own  interests,  for  not  only  is  disease 
no  respecter  of  persons,  but  its  transmission  and  dis- 
semination depend  very  much  upon  one's  relationships 
with  others. 

The  student  will  readily  see  that  the  scope  of  the 
science  is  so  vast  that  in  a  limited  work  like  the  present 
one  it  would  be  impossible  to  go  over  the  entire  ground 
completely  and  thoroughly.  The  most  that  may  be 
attempted  will  be  to  discuss  its  fundamental  laws  as  we 
now  understand  them,  especially  those  that  are  most 
closely  connected  with  the  conscientious  physician's  duties 
and  practice,  and  to  show  the  reasons  for,  and  the  advan- 
tages resulting  from,  the  pursuit  of  hygienic  measures  and 
sanitary  methods  based  on  those  laws  and  our  experi- 
ence. Hygiene  is,  however,  a  science  in  the  study  of 
which  common-sense  must  be  freely  used;  and  if  the 
student  will  only  bring  this  to  his  aid  and  add  to  it 
sincere  consideration,  he  will  speedily  find  that  there  is 
little  that  is  difficult,  beyond  his  grasp,  or  less  than  really 
fascinating. 

It  has  always  been,  as  it  always  will  be,  an  art  to  pre- 
serve health  and  to  ward  off  disease.  Hippocrates  (400  B.C.) 


20  INTRODUCTION 

was  among  the  first  to  define  principles  of  public  health  or 
sanitation.  He  summed  up  the  knowledge  of  his  day 
concerning  hygiene  under  six  headings,  viz.:  Air,  Ali- 
ment, Exercise  and  Rest,  Sleep  and  Wakefulness,  Reple- 
tion and  Evacuation,  and  the  Passions  and  Affections  of 
the  Mind;  and  he  even  pointed  out  that  there  must  be 
an  exact  balance  between  food  and  exercise,  and  that 
"disease  would  result  from  excess  in  either  direction."^ 

The  excellence  of  the  Mosaic  code  is  acknowledged  by 
all  sanitary  authorities,  and  the  effects  of  its  observance 
are  seen  to  this  day  in  the  comparative  longevity  of  the 
Hebrew  race.  The  Greeks  cultivated  to  the  extreme  both 
the  physical  and  mental  faculties  and  had  for  their  motto, 
A  sane  mind  in  a  sound  body.  Recognizing  the  triune 
nature  of  humanity,  we  shall  do  well  if  we  include  with 
these  the  cultivation  also  of  a  spiritual  health.  The 
Romans,  in  their  aqueducts  for  conveying  water  to  the  city 
and  in  the  cloaca  maxima,  have  left  examples  of  sanitary 
engineering  which  are,  in  certain  respects,  not  yet  sur- 
passed. All  of  which  serves  to  show  that  the  ancients 
appreciated  the  importance  of  maintaining  and  improving 
health,  and  the  influence  of  material  conditions  and 
environment  upon  sanitation. 

The  development  of  hygiene  as  a  science,  however,  has 
been  within  comparatively  recent  years.  Perhaps  the 
first  great  impulse  among  English-speaking  peoples,  espe- 
cially in  matters  pertaining  to  sanitation  or  "State  Medi- 
cine," can  be  traced  to  the  labors  of  Dr.  William  Farr, 
and  to  the  establishment,  through  his  efforts,  of  the 
British  Registrar-General's  Office  in  1838.^     Since  then 

1  Treatise  on  Airs,  Waters,  and  Places.     (About  400  b.c.) 

2  Note  should  be  made,  however,  of  the  writings  of  Johannes  Petrus 
Frank,  in  the  first  quarter  of  the  nineteenth  century  and  even  earlier, 
and  of  Parent  DuChatelet,  between  1820  and  1836.  Of  the  work  of  the 
former,  it  has  been  said  that  "It  was  the  first  orderly  presentation  of 
that  which  had  hitherto  been  known  upon  these  subjects,  and  was  the 
first  systematic  effort  to  rescue  from  chaos  such  useful  information  as 
might  be  of  service  in  the  organization  of  a  department  of  sanitary 
supervisors,  or,  as  the  author  preferred  to  call  them,  medical  police." 
A.  C.  Abbott,  University  Medical  Magazine,  July,  1900. 


VALUE  OF  SANITATION  21 

the  task  of  determining  the  principles  and  laws  of  health 
has  been  carried  on  with  unflagging  zeal  by  workers 
both  here  and  abroad,  and  within  the  last  forty  years 
the  knowledge  gained  in  the  new  study  of  the  bacteria 
and  other  microorganisms  and  their  hosts,  especially 
that  regarding  the  causation  and  nature  of  infectious 
diseases,  has  furnished  us  with  a  wealth  of  iacts  with 
and  by  which  we  may  make  the  foundations  of  our 
science  more  lasting  and  secure. 

It  would  be  wrong,  nevertheless,  to  give  the  impression 
that  hygiene  is  as  yet  an  exact  science.  While  it  is 
rapidly  attracting  popular  notice  and  attention,  and  has 
under  the  broader  and  more  altruistic  development 
already  referred  to,  attained  within  comparatively  recent 
years  a  dignity  that  it  did  not  hitherto  have  in  this  new 
world,  it  is  on  a  somewhat  firmer  basis  abroad.  Some  of 
the  best  minds  of  the  time  are  busy  with  many  of  its 
problems,  and  facts  and  laws  are  being  made  clear  that 
more  firmly  fix  or  may  altogether  change  some  of  our 
beliefs  and  our  practise.  Especially  is  such  new  knowl- 
edge to  be  sought  for  in  the  study  of  the  prevention  of 
disease,  the  domain  of  bacteriology  and  the  parasitic 
diseases,  and  physiologic  and  biologic  chemistry. 

Perhaps  a  few  statistics  will  help  one  to  realize  that  the 
study  is  not  in  vain,  and  that  the  promise  of  the  future  is 
even  more  brilliant  than  the  results  and  achievements  of 
the  past.  Three  centuries  ago  the  death-rate  of  London 
was  more  than  80  per  1000;  now  it  is  about  15  per 
1000.  It  is  computed  that  in  the  eighteenth  century — 
the  one  preceding  the  introduction  of  vaccination — fifty 
millions  of  people  died  in  Europe  of  smallpox  alone; 
now  it  is  almost  an  extinct  disease  where  vaccination 
is  compulsory,  as  in  Germany.  In  1872  Sir  John 
Simon  estimated  "that  the  deaths  which  occur  in 
England  are  fully  a  third  more  numerous  than  they 
would  be  if  our  existing  knowledge  of  the  chief  causes 
of  disease  were  reasonably  well  applied  throughout  the 
country,  and  that  of  deaths  which  in  this  sense  may  be 


22  INTRODUCTION 

called  preventable,  the  average  yearly  number  in  Eng- 
land and  Wales  is  about  120,000."  This  result  was 
actually  more  than  achieved  by  1889,  and  in  1912  the 
mortality-rate  for  these  countries  had  fallen  to  13.3  per 
1000  of  population  as  compared  with  an  average  of  22.6 
for  the  decade  1862-71,  this  representing  a  saving  of  over 
300,000  lives  in  the  later  year. 

In  this  country  a  like  improvement  is  to  be  noted, 
though  it  is  only  within  the  last  few  decades  that  much 
attention  has  been  given  to  sanitary  affairs.  The  death- 
rate  of  most  of  our  cities  is  being  progressively  lowered, 
though  the  populations  are  constantly  increased  by  large 
numbers  of  ignorant  and  uncleanly  immigrants.  Im- 
proved sanitary  laws  are  being  enacted  and  enforced, 
streets  better  paved  and  cared  for,  houses  more  wisely 
constructed  and  ventilated,  more  attention  given  to  iso- 
lating the  sick  and  protecting  the  well,  and  the  people 
in  general  are  awakening  to  the  importance  of  improving 
as  well  as  maintaining  the  public  health.  New  York 
City  has  reduced  her  death-rate  per  thousand  within 
twenty-five  years  (1890  to  1915)  from  25.4  to  13.9; 
Chicago,  from  19.1  to  14.3;  Philadelphia,  from  20.76  to 
15.6;  Boston,  from  23.4  to  16.1,  etc.^ 

Notwithstanding  the  increase  in  population,  there  were 
actually  7780  fewer  deaths  in  New  York  City  (Manhat- 
tan Borough)  in  1916  than  in  1891,  although  the  increase 
in  population  during  this  period  was  over  50  per  cent., 
or  almost  one  million  of  additional  citizens.  Similar 
encouraging,  if  not  so  striking,  reports  from  many  other 
cities  enable  their  authorities  to  attribute  the  good 
results  to  advance  in  medical  and  surgical  knowledge 
along  the  lines  of  preventive  medicine,  improved  sani- 
tary surroundings,  better  water-supplies,  cleaner  streets,  in- 

^  The  importance  of  such  statistics  is  not  fully  appreciated  Unless  the 
reader  remembers  that  in  a  city  of,  say,  a  million  inhabitants  a  reduc- 
tion of  the  death-rate  bj'  one  point  means  the  saving  of  one  thousand  lives 
annually. 


RECENT  VITAL  STATISTICS 


23 


inspection  of  milk-  and  food-supplies,  isolation  and  modem 
treatment  of  infectious  diseases,  additional  public  parks,  etc.* 


Death  Rates    per   Thousamd  of  Population 


13 


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Fig.  1. — A  comparison  of  urban  and  rural  mortality  (in  registration 
states  as  constituted  in  1900)  from  all  causes. 


COMPARATIVE  DECLINE  IN  URBAN  AND  RURAL  MORTALITY  (IN 

REGISTRATION  STATES  AS  CONSTITUTED  IN  1900) 

FROM  ALL  CAUSES. 

Decline  in 
'—Death-rates   per   1000   of  population.-^       doath-rate 

Av'ge       Av'Ke      •12fronj'00. 
1900.    1905.    1910.    1912.    'Ol-'OS.    'OS-'Og.    Actual.  Pet. 
Registration  states  17.2     15.9     15.6     14.6       15.9         15.5 

Rural  part  of  registra- 
tion states    .  15.2     14.4     14.7     13.9       14. 
Cities  in  registration 
states      .... 


18.9     17.1     16.2     14.9       17.4 


14.2 
16.4 


2.6  15.1 
1.3  8.5 
4.0    21.2 


1  Twelfth  Census  of  the  United  States,  1900,  vol.  iii;  Vital  Stotistics. 
Part  I;  and  The  Census  Bulletin  (104)  on  Mortality  Statistics  for  1908. 


24  INTRODUCTION 

Other  evidences  of  the  benefits  resulting  from  the  appK- 
cation  of  the  principles  of  modern  hygiene  are  the  marked 
reduction  in  the  sick-  and  death-rates  due  to  infectious 
diseases,  and  the  gradual  increase  in  the  average  expecta- 
tion of  life  in  those  countries  or  places  where  systematic 
prophylactic  and  sanitary  work  is  being  done.  Thus,  in 
the  so-called  "registration-area"  of  the  United  States  the 
death-rate  for  diphtheria  has  dropped  from  70.1  per 
100,000  of  population  in  1890  to  14.5  in  1916;  that  of 
malarial  fever,  from  22.1  to  3;  of  typhoid  fever,  from 
46.3  to  13.3;  and  of  tuberculosis,  from  245.4  to  141.6; 
while  the  general  death-rate  of  the  same  'area"  has  fallen 
in  the  same  period  of  time  from  19.6  to  14  per  1000  of 
population.^ 

Likewise,  the  average  duration  of  life,  according  to 
high  authority,  is  rapidly  increasing — e.  g.,  the  rate  of 
increase  in  Europe  "during  the  latter  half  of  the  nine- 
teenth century  was  about  seventeen  years  per  century, 
and  in  Germany,  where  medical  and  sanitary  science 
has  reached  the  highest  development,  about  twenty-seven 
years  per  century."  The  only  comparative  statistics 
available  in  this  country  are  for  Massachusetts,  where 
life  is  lengthening  at  the  rate  of  about  fourteen  years 
per  century .2  Who  then  shall  say  that  the  study  and 
practice  of  hygiene  and  sanitation — of  preventive  medi- 
cine— is  of  no  practical  value  ? 

It  will  be  well  to  note  at  this  point  the  marked  reflex 
influence  that  the  adoption  of  an  accurate  or  improved 
method  for  the  registration  of  vital  statistics  has  upon 
the  sanitary  status  of  any  part  of  the  population.  Wher- 
ever a  city  or  a  State  has  adopted  such  a  method  there 

1  It  should  be  noted  that  the  above  rates  are  not  strictly  comparable, 
as  the  "registration  area"  has  been  materially  changed  and  increased 
during  the  period  in  question.  Thus,  it  represented  40.5  per  cent,  of 
the  population  and  but  7.1  per  cent,  of  the  land  area  of  the  country  in 
1890,  as  against  70.2  per  cent,  of  the  population  and  44  per  cent,  of 
the  land  area  in  1916. 

2  Report  on  National  Vitality,  Its  Waste  and  Conservation:  Irving 
Fisher,  1909. 


CONTINUOUS  PROPHYLAXIS  NECESSARY        25 

has  almost  immediately  followed  an  improvement  in  its 
morbidity-  and  mortality-rates,  for  which  reason  the 
conditions  obtaining  in  the  component  parts  of  the  total 
''registration-area"  of  the  United  States  are  undoubtedly 
better  than  in  similar  or  comparable  portions  of  the 
remainder  of  the  country.  The  registration-area  is  con- 
sidered to  be  the  combined  areas  or  localities  where,  in 
census  years,  "the  deaths  obtained  from  registration 
sources  constituted  90  or  more  per  cent,  of  the  total 
(registration  plus  additions  from  enumerators),  and  the 
additions  from  the  census  enumerators'  returns  did  not 
exceed  20  per  cent,  of  the  number  reported  by  them"; 
and,  in  other  than  census  years,  where  a  similar  accuracy 
of  official  registration  of  vital  statistics  obtains. 

Nevertheless,  there  is  still  much  to  be  done.  Tuber- 
culosis, which  is  said  to  cause  from  one-seventh  to  one- 
fourth  of  all  the  deaths  in  the  civilized  world,  is  a  pre- 
ventable disease,  and  we  now  not  only  know  its  cause,  but 
also  have  efficient  means  for  cure  in  a  large  proportion 
of  cases,  as  well  as  for  its  general  prevention.  So  with 
a  number  of  the  other  infectious  diseases.  Almost 
every  day  marks  an  increase  in  our  knowledge  of  their 
etiology  and  the  securing  of  immunity  from  them;  and 
not  only  must  physicians  make  use  of  this  knowledge 
as  they  acquire  it,  and  employ  their  utmost  endeavors  to 
secure  the  enactment  and  enforcement  of  sanitary  laws  and 
regulations,  but  they  must  also  realize  that  a  large  part  of 
their  work  lies  in  the  enlightenment  and  education  of  the 
people  in  all  matters  pertaining  to  the  public  health.^ 

The  plague  that  was  the  bane  of  Europe  centuries  ago 

^  It  is  encouraging  to  find  that,  although  over  10.5  per  cent,  of  the  whole 
number  of  deaths  recorded  in  Philadelphia  in  1916  were  caused  by  con- 
sumption, a  progressive  and  marked  lowering  of  the  death-rate  from 
this  disease  in  that  city  is  taking  place,  and  that,  notwithstanding  an 
increase  in  population  of  76  per  cent.,  the  fatalities  from  this  disease 
are  but  few  more  in  number  than  they  were  over  thirty  years  earlier. 
For  example,  the  deaths  from  pulmonary  tuberculosis  in  1885  numbered 
2821,  and  in  1886  were  2834,  rates  respectively  of  297  and  292  per  100,000; 
while  in  19  16  there  were  only  2916  deaths,  or  a  rate  of  170.6  per  100,000 
living. 


26  INTRODUCTION 

and  that  has  been  a  scourge  to  Asia  since,  occasionally 
threatens  us  at  our  western  gates  and  is  rife  in  some  of 
our  newly  acquired  colonial  possessions.  The  infectivity 
of  pneumonia  is  not  appreciated  by  the  laity  nor  by  many 
physicians.  The  death-rate  (137.3)  in  the  Registration 
area  in  1916  due  to  all  forms  of  this  disease  was  almost 
as  high  as  that  for  tuberculosis  of  the  lungs  (141.6)  and 
was  only  exceeded  by  the  latter  and  by  that  for  acute 
endocarditis  and  other  organic  diseases  of  the  heart 
(150.1).  We  must  not  forget  that  pneumonia,  which 
can  be  so  pestilent,  is  "more  or  less  limited  to  centers, 
corresponding  in  the  main  to  the  most  densely  popu- 
lated area,  with  their  allied  conditions  of  squalor  and 
poverty,"^  and  that  it  is  our  duty  and  for  our  own  safety 
to  improve  the  sanitary  conditions  and  environments  of 
such  areas  and  centers.  With  our  present  knowledge  of 
the  value  of  vaccination,  there  have  been  far  too  many 
epidemics  of  smallpox  within  comparatively  recent  years  ? 
Carelessness  in  the  application  of  protective  measures  has 
cost  many  lives  and  much  money.  There  can  be  no  safe 
cessation  in  prophylactic  efforts.  So,  also,  each  and  every 
one  of  the  communicable  maladies  must  be  continually 
investigated  and  studied,  and  all  positive  information 
gained  concerning  them  must  in  turn  be  imparted  to  the 
people  who  need  protection  against  them.  On  the  other 
hand,  it  is  becoming  more  and  more  evident  that  any 
community  may  have  good  health,  that  is  willing  to  pay 
for  it,  and  that  low  sick-  and  death-rates  largely  depend 
upon  an  efficient  administration  of  the  functions  of  public 
health  service. 

Order  of  Study. — In  the  preparation  for  a  study  like 
the  one  on  which  we  are  about  to  enter  there  is  some  ques- 
tion as  to  just  what  may  be  the  most  advantageous  order 
and  arrangement  of  the  subjects  to  be  treated.    For  in- 

1  J.  M.  Anders,  Journal  of  American  Medical  Association,  May  9,  1903. 

2  The  deaths  from  smallpox  in  the  registration-area  of  the  United 
States  for  the  years  1900  to  1904,  inclusive,  numbered  5898,  this  repre- 
senting an  average  annual  death-rate  of  3.7  per  100,000  of  population. 


DUTY  OF  PHYSICIANS  27 

stance,  it  would  be  interesting  to  discuss  our  science  in  its 
relation,  in  turn,  to  the  individual,  the  household,  and  the 
people  in  general — that  is,  personal,  domestic,  and  public 
hygiene;  and  to  show  wherein  the  treatment  of  these  sub- 
divisions is  similar  and  wherein  they  differ.  Such  a  three- 
fold consideration  would  be  not  only  logical,  but  extremely 
instructive  as  w^ell. 

However,  since  the  bacteria  and  other  microorganisms 
have  been  shown  to  have  so  important  a  part  in  many  of 
the  processes  intimately  connected  with  health  and  disease, 
it  will  doubtless  be  advisable  to  devote  the  next  chapter 
to  a  brief  review  of  the  science  of  parasitology.  This 
done,  it  seems  to  the  writer  that  we  shall,  as  beginners 
obtain  a  more  comprehensive  and  thorough  view  of  our 
subject  if  we  pursue  a  method  somewhat  as  follows: 
First,  to  discuss  air,  water,  and  food — three  things  essen- 
tial to  life — in  the  varying  conditions  and  circumstances 
under  which  they  may  affect  the  physical  welfare,  either 
for  good  or  bad,  of  the  individual  or  of  the  community. 
Then  to  take  up,  in  such  order  as  may  seem  best,  the 
other  themes,  such  as  climatology,  habitations,  disinfec- 
tion and  quarantine,  disposal  of  sewage,  clothing,  exercise, 
school  hygiene,  etc.,  whose  consideration,  on  account  of 
their  influence  in  the  preservation  of  health  and  prevention 
of  disease,  is  only  a  degree  less  important  than  those  already 
mentioned.  In  this  way,  while  the  whole  ground  may  not  be 
covered,  the  importance  of  the  various  subdivisions  may 
be  estimated  in  their  relationship  to  one  another,  and  we 
shall  be  the  better  prepared  to  pursue  the  study  as  later 
opportunity  may  offer. 

It  is  doubtless  in  place  just  here  to  review  briefly  the 
reasons  why  it  is  the  special  duty  of  the  physician  to  be 
able  to  recognize  and  correct  insanitary  conditions  where- 
ever  they  may  be  found,  and  why  he  should  make  par- 
ticular and  constant  study  of  the  science  in  all  its  branches 
and  developments. 

Every  true  physician  soon  finds  that  the  respect  and 
affection  of  his  patients  and  associates  are  worth  far  more 


28  INTRODUCTION 

than  mere  mercenary  gain,  and  that  his  highest  aim  should 
be  to  prevent  disease  rather  than  simply  to  cure  it;  and, 
though  this  may  seem  to  militate  against  his  personal  in- 
terests, he  is  unworthy  the  name  of  physician  if  his  object 
and  purpose  be  solely  or  primarily  to  make  money.  How- 
ever, the  observer  quickly  learns  that  in  a  community 
kept  in  good  health  and  sanitary  condition  there  will 
always  be  more  or  less  need  of  a  doctor's  services  in 
spite  of  every  effort  to  prevent  sickness,  and  that  such  a 
community  will  pay  more  promptly  and  more  liberally 
for  such  services  than  one  in  which  sanitary  precau- 
tions are  neglected.  Health  means  ability  to  work  and 
to  earn  good  wages;  and  a  healthy  community  means 
more  business,  more  money,  and  more  comforts.  More- 
over, as  a  rule,  good  wages  insure  prompt  and  willing 
payment  of  the  doctor's  bills  as  well  as  of  others.  We 
may  note  here  the  close  relations  existing  between  sanitary 
science  and  social  and  political  economy — a  relationship 
which  is  very  intimate,  as  we  shall  see  from  time  to  time 
in  our  work,  for  as.  the  physical  condition  of  a  people  is 
bettered,  it  becomes  more  possible  and  more  certain  that 
they  will  likewise  improve  both  mentally  and  morally. 

Again,  though  the  science  of  hygiene  and  sanitation  is 
comparatively  a  new  one,  public  attention  is  being  strongly 
directed  toward  it,  not  only  because  it  vitally  interests 
every  one,  but  because  new  discoveries  and  new  appli- 
cations of  the  laws  pertaining  to  it  are  being  constantly 
made,  which  are,  in  turn,  swiftly  given  to  the  world  by 
both  the  scientific  and  the  popular  press.  This  creates  a 
demand  for  first-class  investigators,  teachers  and  workers, 
which  demand  is  bound  to  increase  in  the  near  future  and 
promises  materially  to  exceed  the  supply.  In  fact,  within 
a  very  few  years  not  only  the  medical  but  also  the  academic 
and  scientific  schools  of  the  country  will  doubtless  be 
compelled  by  public  opinion  to  establish  in  their  faculties 
well-equipped  and  liberally  endowed  chairs  of  hygiene 
and  sanitary  science,  and  it  will  be  from  the  ranks  of  the 
educated  physicians  of  the  country  that  these  teachers 


NEED  FOR  TEACHERS  AND  SANITARIANS        29 

and  scientists  must  naturally  come.  It  will  not  be  long 
before  the  people  in  general  realize  that  it  is  fully  as 
important  that  the  college  student  or  graduate  be 
instructed  how  to  do  his  part  in  taking  care  of  the 
health  of  himself,  his  future  family  and  the  community  in 
which  he  is  to  reside,  as  that  he  shall  be  well  taught  in 
the  abstract  principles  of  theology  or  the  classics  of  dead 
languages. 

So,  also,  considerably  more  time  and  attention  than  are 
now  accorded  to  it  should  be  given  to  hygiene  in  the  work 
of  the  various  normal  schools  for  teachers.  The  graduates 
of  these  schools  will  have  much  of  the  physical  as  well  as 
the  mental  welfare  of  thousands  of  young  and  growing 
children  in  their  keeping,  and  it  is  unquestionably  their 
duty  to  prevent  or  obviate  the  ills  of  school-life  as  far 
as  lies  in  their  power,  and  to  inculcate  and  give  instruc- 
tion in  habits  of  living  which  will  continually  tend  to 
preserve  and  improve  the  physical  health  of  those  under 
their  care.  The  large  proportion  of  young  men  in  this 
country  recently  rejected  as  being  unfit  for  military 
service  because  of  physical  deficiencies  has  awakened 
public  interest  to  the  importance  of  this  subject  as  never 
before  and  methods  and  means  are  being  sought  whereby 
the  tremendous  loss  in  economic  efficiency  due  to  this 
cause  may  be  prevented. 

There  is  also  need  for  trained  sanitarians  in  the  service 
of  the  various  states  and  the  large  municipalities,  and 
there  is  now  an  actual  demand  for  such  men  and  women 
with  no  corresponding  supply  in  view. 

Lastly,  the  time  has  come  when  a  physician  must  neces- 
sarily have  a  knowledge  of  hygiene,  preventive  medicine, 
and  sanitary  science.  Many  states  require  as  thorough 
examinations  in  this  as  in  any  other  branch  of  medicine 
before  granting  the  right  to  practise  within  their  boun- 
daries. Even  more  so  do  the  Army  Medical,  the  Navy 
Medical  and  the  Public  Health  Services  of  the  Government, 
lay  stress  on  this  branch  and  the  constant  demand  for  an 
increased  personnel  in  each  of  these  as  well  as  the  experi- 


30  INTRODUCTION 

ence  gained  by  all  three  during  the  late  world  war,  must 
emphasize  the  value  and  necessity  of  a  thorough  knowledge 
of  hygiene,  sanitation  and  preventive  medicine  on  the 
part  of  those  who  may  anticipate  enrollment  in  any  one 
of  these  branches  of  the  public  service. 

Moreover,  the  people  generally,  as  has  been  intimated, 
are  awakening  to  an  interest  in  sanitary  matters  and  the 
prevention  of  disease,  and  expect  their  physicians  to  be 
well  versed  on  all  pertaining  subjects;  if  they  find  one 
lacking  in  knowledge  or  interest  in  this  respect,  they  are 
apt  to  think,  rightly  or  wrongly,  that  he  will  also  be 
deficient  in  the  other  branches  of  medicine. 

Happily  these  causes  all  combine  to  place  preventive 
on  the  same  high  plane  with  curative  medicine,  and  the 
time  has  passed  in  which  the  chair  of  hygiene  and  pre- 
ventive medicine  did  not  have  a  primary  place  in  any 
thorough  medical  school.  May  the  day  soon  come  when 
it  shall  have  at  least  equal  importance  in  the  curricula 
of  all  academic  and  normal  colleges  and  schools! 

It  is  evident  that  the  successful  physician  and  practical 
student  of  hygiene  must  have  a  thorough  knowledge  of 
three  things:  (1)  Health  and  its  laws;  how  to  obtain  and 
preserve  it.  This  of  course,  implies  a  knowledge  of  the 
human  body  and  its  functions,  viz.,  of  anatomy,  physi- 
ology, and  physiologic  chemistry.  2.  Disease  and  its 
causes  and  nature.  He  must  also  understand  the  dis- 
tinction between  diseases  due  to  causes  external  and 
those  due  to  causes  internal  to  the  body;  and  that  while 
some  of  these  causes  may  be  prevented  or  modified, 
others,  with  our  present  knowledge,  may  not  be  so  readily 
overcome.  3.  Therapeutic  agents,  both  preventive  and 
curative.  He  must  be  conversant  with  and  know  how  to 
use  those  which  he  has  at  his  disposal,  including  not  only 
drugs,  but  also  all  substances  and  forces  that  he  can  make 
efficacious  to  his  purpose.  The  workman  must  know  his 
tools  to  be  able  to  use  them  intelligently. 

Health  is  "that  condition  of  the  body  and  its  organs 
necessary   to   the   proper   performance   of   their   normal 


DEFINITION  OF  HEALTH  AND  DISEASE         31 

functions";  and  disease  may  be  defined  as  "a  condition 
of  the  body  marked  by  inharmonious  action  of  one  or 
more  of  the  various  tissues  or  organs,  owing  to  abnormal 
condition  or  structural  change."  It  is,  accordingly,  well 
to  consider  briefly  the  nature  and  causes  of  disease,  that 
we  may  the  better  understand  the  influence  upon  its  pre- 
vention or  production  of  all  those  varying  factors,  phases, 
and  conditions  of  our  environment  which  we  hope  to 
study  in  our  work. 

Disease  is  a  pathological  or  abnormal  physiological  state, 
not  a  spiritual  thing;  a  condition,  not  a  theory.  Conse- 
quently it  is  to  be  fought  and,  if  possible,  conquered  with 
matter,  natural  forces,  and  physical  means,  though  not 
necessarily  with  violence.  In  fact,  when  once  we  under-/ 
stand  the  minuteness  and  delicate  structure  of  the  ulti- 
mate cells  and  tissues  affected,  we  realize  that  oftentimes 
the  gentlest  application  of  the  forces  and  means  employed 
may  be  the  most  helpful  and  efficient.  But  when  one 
has  seen  the  ravages  caused  by  disease,  as  revealed  in 
the  pathological  laboratory  and  at  autopsies,  not  to  speak 
of  its  manifestations  in  the  living  as  seen  in  the  sick- 
room and  in  hospitals,  I  am  sure  that  he  cannot  logically, 
even  for  a  moment,  give  credence  to  those  who  proclaim 
that  it  can  be  dissipated  by  the  mere  action  of  mind  or  of 
faith  or  by  any  other  than  rational  and  scientific  meas- 
ures. Virchow  gave  a  priceless  boon  to  modern  medicine 
in  his  theory  of  cellular  pathology  and  in  showing  its 
superiority  to  the  old  humoral  theories  and  a  priori  rea- 
soning. He  wrote  "  whatever  outside  of  a  cell  acts  upon 
it  (abnormally),  works  a  mechanical  or  chemical  change 
within  it,  which  change  is  disorder  or  disease."  The 
sooner  we  realize  that  the  laws  of  physics  and  chemistry 
govern  cell  life  and  action  and,  consequently,  the  func- 
tions and  organs  of  the  body,  the  more  accurate  will  be 
the  treatment  and  the  more  certain  the  prevention  of 
disease. 

For  convenience  sake,  diseases  may  be  divided  into  two 
main  classes,  somewhat  different  in  their  origin,  nature, 


32  INTRODUCTION 

and  character,  although  the  line  between  the  two  is  not 
always  clearly  marked.  Diseases  of  the  first  class  arise 
within  the  body,  and  may  be  called  autogenetic.  They 
are  usually  due  to  some  alteration  or  disturbance  of  nu- 
trition and  assimilation,  such  as  irregular  absorption  of 
products  of  digestion;  or  of  function,  such  as  that  of  elimi- 
nation, to  either  of  which,  as  well  as  to  other  similar 
causes,  various  auto-intoxications  may  be  due.  The  sec- 
ond class  comprises  those  which  are  due  to  causes  from 
without,  favored,  it  may  be,  by  either  internal  or  external 
predisposing  conditions,  but  each  malady  of  necessity 
depending  upon  the  reception  or  inoculation  of  the  spe- 
cial cause,  which  cause  has  the  power  of  reproduction  and 
development,  of  vitality  and  virulence.  Such  diseases 
are  called  contagious,  infectious,  specific,  inoculable,  or 
zymotic.^ 

In  the  first  class,  with  our  present  knowledge,  we 
may  place  such  maladies  as  gout,  diabetes,  neurasthenia, 
etc.;  while  into  the  second  will  obviously  fall  all  that  are 
now  known  to  be  due  to  living  "germs"  or  organisms, 
such  as  cholera,  typhoid  fever,  malaria,  etc.  However, 
we  must  not  overlook  the  impulses  often  given  to  the 
causation  of  certain  members  of  the  second  class  by  faulty 
conditions  of  nutrition  or  assimilation,  as  is  especially 
exemplified  in  many  cases  of  tuberculosis.  The  char- 
acter of  the  soil  may  influence  the  growth  and  product 
of  a  plant  almost  as  much  as  the  species  itself,  and  so  the 
difference  in  constitution  and  tissue  of  individuals  may 

1  In  this  connection  the  following  quotation  from  Sedgwick  is  inter- 
esting: "Diseases  may  be  regarded  as  due  either  to  defects  in  the  con- 
stitution or  construction  of  the  vital  mechanism,  or  else  to  external 
unfavorable  influences  acting  upon  it.  From  the  point  of  view  of  origin 
or  causation,  all  diseases  may  be  divided  into  two  classes,  viz.:  (I)  Consti- 
tutional, or  (II)  Environmental.  This  classification,  while  open  to  many 
objections,  is  of  the  highest  value  to  the  physiologist  and  the  sanitarian, 
for  it  brings  the  former  lace  to  face  with  intrinsic,  structural,  or  organic 
defects  in  the  mechanism,  while  the  attention  of  the  latter  is  concen- 
trated upon  those  abnormal  external  influences  which  act  unfavorably 
upon  the  organism,  and  which  he  must  seek,  and  may  be  able  to  re- 
move."    Principles  of  Sanitary  Science  and  Public  Health,  1902,  p.  10. 


PROPHYLAXIS  33 

materially  determine  the  variations  in  symptoms  and  viru- 
lence so  often  manifested  by  an  infectious  malady. 

A  third  class  or  a  subdivision  of  diseases  might  also  be 
indicated,  which  would  include  those  disturbances  which 
are  almost  purely  psychical  and  whose  symptoms  are 
largely  notional  and  the  result  of  perverted  imagination 
or  coordination.  But  it  is  a  question  whether  the  primary 
cause  of  almost  all  such  disorders  is  not  an  altered  and 
abnormal  nutrition  or  functioning  of  the  general  nervous 
economy  of  the  body  or  the  symptoms  simply  reflex 
manifestations  of  irritative  disturbances  of  distant  organs. 

Prophylaxis  is  "the  use  of  hygienic  or  other  precau- 
tions conducive  to  the  prevention  of  disease";  or  it  may 
be  defined  as  "  a  series  of  methods  or  procedures  whereby 
disease  is  restricted  and  prevented  by  suppressing  or  re- 
moving its  predisposing  conditions,  and  destroying  or 
modifying  the  exciting  causes."  Its  first  function  of  sup- 
pressing or  removing  predisposing  conditions  is  accom- 
plished by  sanitation;  the  second,  that  of  destroying  or 
modifying  exciting  causes,  is  carried  out  by  disinfection. 
The  term  "predisposing  conditions"  should  be  used  in- 
stead of  "predisposing  causes,"  because  these  conditions,, 
cannot  in  themselves  originate  a  disease,  though  they  may 
make  the  system  more  susceptible  to  the  exciting  causes 
of  a  disease.  For  example,  the  predisposing  factors  of 
tuberculosis — "privation,  depression,  and  excess" — are 
conditions,  and  though  they  often  prepare  the  tissues  for 
the  development  of  the  malady,  it  can  only  occur  after 
infection  by  the  exciting  cause,  viz.,  the  specific  tubercle 
bacillus. 

As  we  have,  as  yet,  little  definite  knowledge  of  the 
exact  nature  of  the  exciting  causes  of  autogenetic  diseases, 
they  being  developed  and  elaborated  within  the  body, 
and  as  disinfection,  or  the  destruction  and  modification 
of  exciting  causes,  is  an  important  feature  of  prophylaxis, 
we  at  present  naturally  look  for  more  immediate  and 
satisfactory  results  in  the  application  of  prophylaxis  to 
the  second  class  of  diseases;  but  this  does  not  prevent  or 
3 


34  INTRODUCTION 

restrict  the  employment  of  certain  prophylactic  measures 
in  regard  to  the  first  class,  such  as  the  selection  of  proper 
diet,  clothing,  climate,  etc.,  and  the  removal  or  counter- 
acting of  all  influences  favoring  malnutrition  or  imperfect 
and  improper  functional  activity.  We  may  therefore 
say  that  sanitation  is  the  defensive,  disinfection  the  ag- 
gressive part  of  prophylaxis. 

To  suppress  and  remove  predisposing  conditions  and  to 
prepare  the  body  to  resist  and  repel  the  action  of  exciting 
causes,  we  must  not  only  strengthen  its  powers  of  resist- 
,  ance,  but  also  make  all  external  media  as  favorable  to 
health  and  as  hostile  to  the  exciting  causes  as  possible. 
The  defensive  powers  of  the  body  must  lie  in  the  indi- 
vidual cells  and  tissues  of  the  body,  including  the  vital 
fluids,  and  it  is  but  reasonable  to  suppose  that  this  repellent 
action  to  noxious  substances  is  best  performed  when  the 
cells  and  tissues  are  in  most  perfect  health  and  most 
vigorous  condition.  This  is  not  only  good  logic,  but  all 
experience  and  scientific  research  go  to  show  that  it  has  a 
firm  foundation  in  fact. 

''''    We  shall  soon  learn  that  purity  of  the  external  media 
and  environment  of  the  body  is  essential  to  its  welfare 
and  that  of  its  component  tissues,  and  that  conditions  of 
impurity  in  these  media  predispose  to  disease.    We  shall 
also  learn  that  a  proper  and  sufficient  supply  of  whole- 
some food  is  essential  to  health,  and  that  certain  other 
factors,  as  sex,  age,  clothing,  climate,  etc.,  may  act  for 
ffood  or  ill  in  the  determination  of  the  balance  between 
{health  and  disease.    In  other  words,  if  we  strengthen  the 
(  resistant  powers  of  the  system  to  the  fullest  extent  and  re- 
move all  predisposing  conditions,  in  all  probability  the 
exciting  causes  will  be  inoperative  in  most  cases,  and  there 
will  be  no  incurrence  of  disease.    This  is  the  essence  of 
sanitation :  to  secure  perfect  health,  to  increase  the  inher- 
ent power  to  resist  noxious  and  harmful  influences,  and 
I  to  make  all  the  surroundings  and  environments  of  the 
^body  safe  and  free  from  depressant  factors.    This  applies 
equally  to  both  classes  of  disease;  for  with  healthy  cells 


PROPHYLAXIS  35 

and  proper  food  there  will  not  be  faulty  nutrition  and 
assimilation  or  improper  functioning  and  the  consequent 
production  of  the  exciting  causes  of  autogenetic  disease; 
and  with  a  vigorous  resistance  and  wholesome  environment 
there  is  little  opportunity  for  the  germs  of  infectious  mala- 
dies to  obtain  a  foothold  within  the  system  long  enough  to 
reproduce  themselves  and  cause  their  characteristic  dis- 
orders. The  best  means,  therefore,  of  preventing  disease 
is  to  learn  and  apply  the  best  methods  of  attaining  and 
retaining  a  healthy  and  vigorous  state  of  the  system,  viz., 
to  determine  and  observe  the  laws  of  hygiene. 


CHi    -lER  II. 
BACTERIOLOGY  AND  PARASITOLOGY. 

The  increase  in  the  knowledge  concerning  the  lowest 
forms  of  life,  and  the  discovery  that  these  often  have  a 
causative  action  in  the  excitation  of  many  maladies, 
have  greatly  facilitated  the  study  of  the  prevention 
of  disease.  In  fact,  it  is  largely  to  this  advance  in 
knowledge  and  to  the  confirmation  of  the  germ  theory 
that  much  of  the  success  of  modern  hygiene  and  sani- 
tation is  due.  In  addition  many  species  of  bacteria  and 
other  microorganisms  are  of  extreme  importance  be- 
cause their  function  is  that  of  scavengers,  continually 
working  to  remove  and  convert  the  useless  and  harmful 
wastes  of  the  world  into  material  of  high  value  as  food 
for  organic  life;  while  still  other  kinds  are  being  found 
to  have  great  value  in  many  strictly  commercial  processes. 
A  review  of  the  chief  facts  concerning  them  will  therefore 
be  in  place  at  this  time. 

The  unicellular  vegetal*  microorganisms  divide  them- 
selves into  two  general  classes  with  respect  to  their  man- 
ner of  reproduction,  viz.,  those  that  multiply  by  budding 
— the  hlastomycetes — and  those  that  increase  by  simple 
division  or  fission — the  schizomycetes.  In  the  first  class 
we  have  the  hyphomycetes  or  mould-fungi,  and  the  sac- 
charomycetes  or  yeasts,  examples  of  these  being  familiar 
to  everyone.  However,  it  is  with  the  fission-fungi,  or 
bacteria  as  they  are  now  more  generally  known,  that  we 
are  most  concerned  as  sanitarians,  since  they  practically 
include  almost  all  those  vegetal  microorganisms  that  are 
more  or  less  closely  connected  with  the  production  of 
disease  as  well  as  with  the  removal  of  offensive  matter. 
Comparatively  few  of  the  yeasts  and  moulds  are  patho- 
genic, and  then  only  indirectly  or  in  a  minor  degree. 
(36) 


CHARACTERISTICS  OF  BACTERIA  37 

Bacteriology,  then,  is  the  science  of  those  unicellular  vegetal 
microorganisms  that  multiply  by  direct  transverse  division 
(fission),  or,  as  occasionally  happens,  by  the  development 
of  spores.  Its  study  consists  in  the  examination  by  means 
of  the  microscope  of  the  form  and  method  of  growth  of 
these  minute  plants,  in  their  artificial  cultivation  on  or  in 
suitable  media,  and  in  the  determination  of  the  effects  of 
the  inoculation  of  pure  cultures  upon  animals.  To  these 
may  be  added  another  field  of  research  that  gives  promisQ^ 
of  much  development  in  the  near  future,  viz.,  the  study 
of  the  chemistry  of  the  bacterial  products  and  of  the  reac- 
tions produced  by  their  presence  in  culture-media  and  in 
living  tissues. 

Although  more  than  two  centuries  have  elapsed  since 
the  discovery  of  the  bacteria  by  Leeuwenhoek  (about 
1680),  and  though  Plenciz  advanced  as  early  as  1762 
what  is  practically  the  germ  theory  of  today,  most  of  our 
knowledge  concerning  the  physiology,  methods  of  cultiva- 
tion, and  differentiation  of  the  bacteria  has  been  acquired 
within  less  than  a  third  of  a  century.  It  is  true  that 
some  earlier  advance  had  been  made  in  sterilization, 
and  that  Cohn,  by  establishing  the  fact  of  spore-formation, 
demolished  the  last  arguments  in  favor  of  spontaneous 
generation  and  confirmed  the  science  of  bacteriology;  but 
until  the  last  three  decades  we  had  but  little  knowl- 
edge as  to  the  means  of  separating  and  isolating  the  differ- 
ent species  and  making  pure  cultures,  or  of  preparing 
culture-media,  staining,  etc. 

As  has  been  intimated,  the  bacteria  are  unicellular 
organisms,  usually  multiplying  by  a  process  of  cell-elonga- 
tion and  fission.  Being  without  chlorophyll,  they  cannot 
absorb  and  decompose  carbon  dioxide  and  ammonia,  as  do 
the  higher  plants;  but  require  for  their  growth  and  nutri- 
tion organic  matter — usually  soluble  albumin — in  the  pres- 
ence of  moisture.^   Hence,  they  must  be  either  saprophytes 

1  It  will  be  understood  that  these  statements  and  many  of  those  to 
follow  are  more  or  less  general,  and  that  certain  species  of  the  bacteria 
may  present  notable  exceptions. 


38 


BACTERIOLOGY  AND  PARASITOLOGY 


or  parasites.  As  the  combination  of  albuminous  organic 
matter  and  water  is  extremely  common,  so  the  distribu- 
tion of  the  bacteria  over  the  earth  is  wide-spread  and  prac- 
tically universal. 

Some  of  the  bacteria  may,  under  adverse  conditions, 
such  as  lack  of  nutriment  or  of  moisture,  too  alkaline  or 
too  acid  a  medium,  extremes  of  temperature,  etc.,  or  on 
the  other  hand,  as  a  result  of  the  attainment  of  a  stage  of 
maximum  development,  produce  spores  which  are  much 
more  strongly  resistant  to  deleterious  influences  than  the 


Fig.  2. — Micrococci  (gonococci)  in  pus-cells.     X  1000. 

bacteria  themselves.  In  this  way  the  spore-forming 
species  may  often  survive  the  action  of  disinfectants  or 
other  agencies  that  are  sufficient  to  destroy  other  bacteria. 
Upon  the  resumption  or  recurrence  of  favorable  conditions 
the  spores  develop  into  cells  similar  in  form  and  nature 
to  their  parent  cells.  It  is  to  be  remembered  that  spores 
do  not  reproduce  spores,  and  that  "a  single  cell  produces 
but  one  spore.  "^ 


Abbott,  Principles  of  Bacteriology,  1st  ed.,  p.  31. 


CLASSIFICATION  OF  BACTERIA  39 

Under  the  microscope  the  spores  are  seen  as  highly 
refractive,  spherical  bodies  that  stain  with  difficulty,  and 
evidently  have  a  very  resistant  envelope,  probably  of  cellu- 
lose. The  interior  of  bacteria  and  spores  is  protoplasm. 
So  far  as  is  positively  known  at  this  time,  only  certain  of 
the  bacilli  form  spores,  while  a  few  of  the  spirilla  and 
one  or  two  species  of  micrococci  probably  have  the  same 
faculty. 

Again,  under  certain  peculiar  conditions  some  organisms 
may  develop  another  morphological  change,  the  so-called 


Fig.  3. — Tubercle  bacilli  in  sputum.     X  1000. 

involution-forms.  These  are  doubtless  pathologically 
distorted  cells,  with  probably  diminished  resisting  powers, 
but  which  will  revert  to  the  normal  type  under  favorable 
conditions,  providing  the  unfavorable  environment  does 
not  kill  them. 

Lastly,  at  times  certain  individuals  of  a  species  seem  to 
have  departed  from  the  typical  form,  but  these  departures 
are  only  different  phases  in  the  normal  development.  Thus 
a  young  bacillus  may  be  shorter  than  the  adult  and  look 
much  like  a  coccus,  or  a  coccus  about  to  undergo  division 


40      BACTERIOLOGY  AND  PARASITOLOGY 

may  be  oval  in  shape  and  considerably  larger  than  the 
quiescent  members  of  its  species.  But  one  form  of 
bacteria  never  permanently  takes  that  of  another — micro- 
cocci are  always  micrococci,  bacilli  always  bacilli,  etc. 

A  thoroughly  scientific  classification  of  the  bacteria  is 
scarcely  possible  as  yet,  owing  to  our  incomplete  knowl- 
edge of  their  character,  method  of  growth,  physiology, 
etc.  However,  there  are  a  number  of  ways  in  which  we 
may  subdivide  them,  none  of  them  exactly  scientific,  per- 
haps, but  still  sufficiently  accurate  and  convenient  for 
our  purpose.  If  we  consider  the  bacteria  as  to  form,  we 
have:  (a)  micrococci,  spherical  in  shape;  (b)  bacilli,  which 
have  one  diameter  longer  than  another;  and  (c)  spirilla, 
spirals  or  segment  of  spirals.^  We  shall  have  more  to  say 
hereafter  of  the  characteristics  of  each  of  these  subdivi- 
sions. Accordingly  as  they  live  best  with  or  without  air  or 
oxygen  they  are  aerobic  or  anaerobic.  Again,  they  may  be 
named  according  to  their  product — e.  g.,  some  produce 
colors,  chromogenic;  others  pus,  pyogenic,  etc.  Lastly, 
they  exist  and  grow  either  as  saprophytes  upon  dead,  or 
as  parasites  upon  living  organic  matter.  We  also  say 
that  an  organism  is  optional  or  facultative  when  it  is  at 
one  time  a  saprophyte  and  at  another  a  parasite,  or  at 
one  time  aerobic  and  again  anaerobic;  and  that  it  is 
obligate  when  it  has  not  this  property  of  changing  its 
nature  according  to  surrounding  conditions. 

Some  of  the  micrococci  are  named  according  to  the 
manner  in  which  they  grow.  If  in  pairs,  they  are  called 
diplococci;  in  fours,  tetracocci;  in  threads,  streptococci, 
etc.  Groups  or  masses  of  micrococci  or  bacilli  held  to- 
gether by  a  gelatinous  substance  are  called  zooglea.  As 
compared  with  other  bacteria,  with  one  or  two  exceptions, 
we  know  but  little   about  the   spirilla.     The  germ  of 


^  Accurately  speaking,  some  of  the  so-called  higher  bacteria  have 
more  elaborate  development  and  distinction  as  to  form,  but  as  our  pres- 
ent discussion  has  almost  entirely  to  do  with  the  phenomena  of  the 
lower  and  simpler  bacteria,  the  former  may  henceforth  be  omitted  from 
the  discussion. 


SEPARATION  OF  SPECIES  41 

cholera— the  comma  bacillus  (?)— belongs  to  this  class, 
and  the  cause  of  relapsing  fever  is  also  probably  a  spirillum. 

Most  of  the  bacteria  thrive  best  in  culture-media  that 
are  neutral  or  only  slightly  alkaline,  though  a  few  species 
seem  to  do  better  in  sHghtly  acid  surroundings.  So,  also, 
they  do  best  at  temperatures  ranging  between  20°  and 
40°  C.  (68°  and  104°  F.),  though  they  may  grow  at  any 
temperature  between  5°  and  43°  C.  (41°  and  109.4°  F.). 
Any  marked  deviation  in  the  culture-media  from  the 
neutral  point  or  continued  exposure  to  extremes  of  tem- 
perature may  either  check  the  growth  of  the  organisms 
altogether,  and  eventually  destroy  them,  or  may  cause 
spore-formation,  or  the  production  of  involution-forms, 
or  a  change  in  the  composition  and  the  character  of  the 
chemical  products  which  the  bacteria  normally  produce. 
This  also  holds  good  with  respect  to  any  other  condition  or 
substance  that  may  be  deleterious  to  the  bacteria  in  their 
normal  state;  wherefore  we  shall  see  that  such  factors  are 
important  as  having  a  decided  influence  in  altering  the 
virulence  of  pathogenic  bacteria  and  in  suggesting  methods 
for  bringing  about  a  condition  of  immunity  to  their 
attacks. 

As  it  is  rare  to  find  isolated  individual  species  anywhere 
except  in  pure  cultures  artificially  prepared,  it  is  evident 
that  we  must  devise  some  way  of  separating  the  different 
kinds  of  organisms  one  from  another.  This  is  best  accom- 
plished by  the  method  suggested  by  Koch,  viz.,  to  intro- 
duce the  mixed  kinds  into  some  melted  culture-medium, 
like  nutrient  gelatin,  which  solidifies  on  cooling,  but 
whose  melting-point  is  not  sufficiently  high  to  destroy 
the  vitality  of  the  germs.  If  the  fluid  be  well  shaken, 
the  various  species  will  be  distributed  through  it,  and,  upon 
cooling,  each  individual  or  group  (zooglea)  of  individuals 
of  the  same  kind  will  be  fixed  in  its  place  and  become  the 
starting-point  of  a  colony  of  that  special  kind.  Moreover, 
if  the  gelatin  before  cooling  be  poured  upon  sterilized 
glass  plates  or  into  flat  (Petri)  dishes  (Fig.  6),  the  subse- 
quent work  of  counting,  examining,  and  making  cultures 


42 


BACTERIOLOGY  AND  PARASITOLOGY 


from  the  colonies  thus  secured  will  be  greatly  facilitated, 
while  by  transplanting  and  repeating  the  process  one  or 


Fig.  4. — Spirillum  of  Asiatic  cholera.     X  1000. 


Fig.  5. — Bacilli  of  hog  cholera,  showing  fiagella.     X  1000. 

more  times,  absolutely  pure  cultures  of  each  species  in 
the  original  mixture  may  be  obtained. 


STERILIZATION  43 

Special  care  must  be  taken  in  this,  as  in  all  other  bacte- 
riological methods  or  operations,  to  prevent  contamination 
of  cultures,  media,  or  apparatus  by  other  organisms  which 
are  almost  omnipresent,  and  which  would  prevent  accurate 
results  or  deductions  were  they  not  rigidly  excluded  or 
destroyed.  Obviously,  we  may  not  use  chemical  disinfect- 
ants or  antiseptics  as  a  means  of  destroying  the  interfering 
microbes,  for  such  procedure  would  kill  or  inhibit  the 
growth  of  the  bacteria  we  desire  to  cultivate;  but  we  must 
sterilize  by  heat  all  the  articles  used,  together  with  their 
contents.  This,  if  properly  done,  does  not  affect  the 
nutrient  properties  of  the  culture-media,  while  it  does 
remove  the  danger  of  contamination  already  present. 

In  sterilizing  we  may  use  either  dry  or  moist  heat,  the 
latter  being  far  more  preferable  in  most  cases,  since  to 


Fig.  6. — Petri  double  dish  (now  generally  used  instead  of  plates). 

be  effectual  it  does  not  require  so  high  a  temperature  nor 
so  long  a  time  as  does  the  former.  Moist  heat,  especially 
in  the  form  of  steam,  is  more  penetrating  than  dry  heat; 
beside,  dry  heat  must  be  of  so  high  a  temperature  that 
it  may  render  useless  for  culture  purposes  such  substances 
as  nutrient  gelatin.  Glassware  and  the  like,  however, 
may  be  quickly  and  advantageously  sterilized  by  dry  heat. 
On  the  other  hand,  certain  substances,  like  blood-serum, 
are  spoiled  for  culture  purposes  even  by  moist  heat  con- 
tinued sufficiently  long  to  kill  the  spores  possibly  present, 
as  the  latter  require  a  higher  temperature  or  more  pro- 
longed heating  to  sterilize  them  than  the  bacteria  without 
spores.  Resort  is  therefore  had  to  fractional  sterilization 
in  such  cases,  exposing  the  materials  for  only  a  short 
time   to   a  temperature  just   sufficient   to  destroy  the 


44 


BACTERIOLOGY  AND  PARASITOLOGY 


bacteria,  repeating  the  process  after  an  interval,  say 
twenty-four  hours,  which  is  presumably  sufficient  to 
allow  the  spores  to  develop  into  bacteria;  and  again  a 
third  time,  after  a  like  interval,  to  insure  absolute  sterili- 
zation. Previous  to  sterilizing  the  culture-media  and 
apparatus  the  test-tubes,  flasks  and  similar  vessels  are 
stoppered  with  plugs  of  cotton-wool  in  order  to  prevent 
the  subsequent  access  of  contaminating  organisms,  and 


Fig.  7. — Steam  sterilizer,  pattern  of  Koch. 

these  are  afterward  covered,  when  necessary,  with  rubber 
caps  or  paraffin  wax  to  prevent  the  evaporation  of  the 
culture-fluids,  or  of  moisture  from  the  gelatin,  etc. 

As  a  basis  for  a  number  of  culture-media  we  may  use 
beef-broth  or  bouillon,  which  is  a  fluid  especially  favor- 
able to  bacterial  growth  in  that  it  contains  an  abundance 
of  albumin  in  solution.  When  a  solid  medium  is  desired, 
either  gelatin  or  agar-agar  (a  gelatin-like  substance 
obtained  from  Japan)  may  be  added  to  bouillon,  giving 


DIFFERENTIATION  OF  SPECIES  45 

nutrient  gelatin  and  nutrient  agar-agar.  Of  these,  the 
gelatin  has  a  melting-point  below  the  temperature  of  the 
human  body,  while  that  of  agar  is  above;  consequently 
we  employ  the  latter  when  it  is  desired  to  cultivate  germs 
that  grow  best  at  the  body  temperature,  although  the 
development  of  most  bacteria  is  usually  more  rapid  and 
characteristic  upon  gelatin.  Blood-serum,  sterilized  and 
solidified,  is  also  used  for  the  cultivation  of  certain  organ- 
isms, such  as  the  diphtheria  bacillus;  and  there  are  certain 


Fig.  8. — Arnold  steam  sterilizer. 

others  which  can  best  be  identified  by  their  difference  in 
growth  upon  boiled  potato,  milk,  etc. 

The  differentiation  of  the  various  species  of  bacteria  is 
to  be  made  by  noting  their  appearance  and  form  under 
the  microscope,  whether  they  are  motile  or  not,  how  they 
take  different  stains,  etc. ;  by  observing  their  methods  of 
growth  in  or  upon  different  culture-media,  and  the  color 
and  appearance  of  the  colonies,  as  well  as  variations  in 
color,  reaction,  etc.,  in  the  culture-media;  by  notmg 
whether  they  are  aerobic  or  anaerobic,  or  facultative,  and 


46  BACTERIOLOGY  AND  PARASITOLOGY 

at  what  temperatures  they  thrive  best,  etc. ;  and  finally  by 
studying  their  action  and  the  effect  of  their  products  upon 
living  animals.  In  this  way  we  may  determine  the  char- 
acteristics of  each  individual  or  species,  and  will  eventually 
have  the  data  for  a  strictly  scientific  classification  of  the 
bacteria  in  general.  For  example,  the  organisms  causing 
suppuration  are  usually  micrococci,  occurring  in  clusters 
(staphylococci)  or  in  chains  (streptococci);  the  cause  of 
typhoid  fever  is  a  bacillus,  and  the  cholera  germ  belongs 
to  the  spirilla.  The  tubercle  bacillus  stains  with  marked 
difficulty,  but  w^hen  stained  is  not  readily  decolorized  by  a 
weak  solution  of  nitric  acid,  as  are  almost  all  other  bacilli. 
Some  bacteria  liquefy  nutrient  gelatin,  others  do  not,  and 
almost  none  liquefy  agar-agar.     This  liquefaction  is  not  a 


Fig.  9. — Ruled  square  for  counting  colonies. 

melting,  but  rather  a  kind  of  peptonization,  since  the 
gelatin  will  not  solidify  after  this  occurs,  as  it  does  after 
being  subjected  to  moderate  warming.  Again,  some  bac- 
teria produce  one  particular  color  or  chemical  substance  in 
the  presence  of  oxygen,  and  another  in  its  absence;  some 
produce  color  only  in  the  light,  others  only  in  the  dark, 
etc.  Finally,  different  pathogenic  microbes  cause  differ- 
ent maladies  when  inoculated  in  animals  or  human  beings, 
and  the  same  germ  may  produce  different  results  in 
animals  of  different  species  or  families.^ 

The  subdivision  of  the  bacteria  into  saprophytes  and 
parasites  has  already  been  noted.    Therefore  it  must  be 

1  See  Kenwood's  Hygienic  Laboratory,  pp.  466-470;   also  McFarland's 
Pathogenic  Bacteria,  pp.  46-57. 


FUNCTIONS  OF  SAPROPHYTES  47 

remembered  that  not  all  of  these  microscopic  plants  are 
disease-producers;  much  the  larger  proportion,  in  fact, 
being  benefactors  rather  than  otherwise  to  the  human 
rac^. 

The  function  of  many  of  the  saprophytic  organisms 
is  to  change  dead  organic  matter  into  simpler  chemical 
compounds  and  ultimately  into  end-products  such  as 


Fig.  10. — Pocket-case  containing  sterilized  culture-tubes,  platinum  needle, 
and  alcohol  lamp,  used  for  obtaining  cultures  for  diagnosis,  etc. 

carbon  dioxide,  ammonia,  and  water,  these  latter  sub- 
stances being  once  more  utilized  in  the  nutrition  of  the 
higher  forms  of  vegetable  life,  which  are  in  turn  necessary 
to  the  existence  of  the  animal  life  upon  the  globe.  One 
should  also  understand  that  some  of  the  saprophytes  in 
the  soil  seem  to  possess  a  constructive  or  synthetic  p)ower, 
elaborating  more  complex  plant-foods  from  the  simple 


48  BACTERIOLOGY  AND  PARASITOLOGY 

compounds  mentioned.  Indeed,  it  is  only  when  the 
student  of  hygiene  fairly  realizes  the  wide  scope  of  the 
functions  of  these  minute  but  almost  omnipresent  scav- 
engers that  he  will  comprehend  the  important  part 
they  play  in  the  purification  of  our  environment.  In 
the  air  they  possibly  help  the  oxygen  to  destroy  the 
harmful  effluvia  and  exhalations  of  men  and  animals 
and  the  floating  debris  of  organic  substances;  in  the 
soil,  the  common  receptacle  of  the  wastes  and  refuse 
of  vital  activity,  they  quickly  and  continually  convert 
these  noxious  additions  into  foods  of  the  highest  value 
to  growing  plants;  in  running  streams  and  quiet  pools 
they  are  of  the  greatest  importance  in  the  removal  of 
the  dangerous  impurities  washed  from  the  surface  of  the 
land  or  recklessly  discharged  from  human  habitations, 
factories,  and  the  like.  And  not  only  do  the  saprophytes 
help  mankind  in  this  way,  but  members  of  the  class  are 
beneficent  in  many  others.  For  example,  they  enable 
those  plants,  the  leguminosse,  which  yield  us  the  largest 
supply  of  vegetable  proteids,  to  derive  much  of  their 
nitrogen  almost  directly  from  the  atmosphere;  they  have 
much  to  do  with  the  flavor  and  value  of  dairy  products, 
and  uses  in  which  they  may  be  employed  in  the  domestic 
and  commercial  affairs  of  life  are  being  newly  announced 
from  day  to  day.  Thus  we  find  the  bacteria  of  this  class, 
which  comprises  by  far  the  greater  number  of  known 
species,  to  be  our  benefactors  and  indispensable  servants 
both  in  preventing  the  accumulation  of  noxious  and  harm- 
ful substances  upon  the  earth,  and  in  helping  to  produce 
the  food  which  we  eat  and  many  other  things  that  we 
need  and  use  in  our  daily  life. 

The  parasitic  bacteria,  on  the  other  hand,  have  their 
habitat  in  or  upon  highly  organized  living  matter,  and 
exist  at  its  expense.  They  may  also  produce  in  their  growth 
poisonous  substances,  called  toxins  and  toxalbumins,  that 
are  either  locally  or  generally  harmful  to  the  organism 
that  is  their  host.  It  is  needless  to  say  that  it  is  in  this 
class  that  we  find  the  disease  germs,  or  pathogens  as  some 


THE  GERM  THEORY  49 

would  call  them.  It  should  not  be  forgotten,  however,  that 
the  saprophytes,  in  bringing  about  the  decomposition  of 
complex  organic  bodies,  may  also  produce  ptomatns,  which 
may  or  may  not  be  toxic  to  animal  life.  Of  these  latter, 
we  may  instance  as  good  examples  the  cadaveric  poison  of 
the  dissecting-room  or  the  dangerous  tyrotoxicon,  a  by  no 
means  uncommon  product  in  the  decomposition  of  milk  or 
ice-cream.  But  though  ptomains  may  be  more  or  less 
characteristic  of  the  respective  bacteria  that  produce 
them,  each  varies  in  its  composition  and  properties  accord- 
ing to  the  substance  upon  or  in  which  it  is  produced, 
while  the  toxins  are  specific  derivatives  or  "active  prin- 
ciples" of  their  respective  micro-organisms.  In  other 
words,  different  kinds  of  saprophytes  may  produce  the 
same  ptomain  from  a  given  organic  substance,  but  each 
toxin  is  the  product  of  its  own  particular  species  of  bacteria 
and  is  independent  of  the  latter's  place  of  growth  or 
environment. 

Considering  for  the  present  the  pathogenic  bacteria 
alone,  we  are  naturally  brought  to  the  discussion  of  the 
gervi  theory,  which  is,  that  the  exciting  cause  of  each 
contagious  or  infectious  disease  is  some  specific  parasitic 
organism,  and  that  each  of  these  diseases  is  only  communi- 
cated by  the  transference  and  development  of  its  par- 
ticular parasite  or  germ  within  or  upon  the  tissues  of  the 
infected  individual.  Consequently  such  diseases  are  trans- 
mitted from  one  person  to  another,  or  in  some  cases  from 
animals  to  men  or  vice  versa,  by  means  of  these  micro- 
organisms, and  the  transference  is  by  air,  water,  food  or 
other  fomites,  or  by  direct  contact.  It  is  evident  that  if 
acquired  knowledge  establishes  the  truth  of  this  theory, 
the  prevention  of  infectious  diseases  is  greatly  simpli- 
fied and  becomes  merely  a  matter  of  combining  effective 
sanitation,  of  which  we  have  spoken,  with  the  destruction 
of  the  specific  exciting  causes — i.  e.,  disinfection.  Nor  is  it 
essential  that  we  any  longer  make  the  distinction  between 
the  terms  contagious,  infectious,  zymotic,  and  specific, 
that  formerly  obtained,  since  they  may  practically  be  used 
4 


50  BACTERIOLOGY  AND  PARASITOLOGY 

synonymously.  The  first  of  these  terms  used  to  be 
apphed  to  those  diseases  which  were  beheved  to  be  trans- 
mitted most  frequently  by  direct  contact,  and  infectious 
to  those  of  which  the  transmission  is  usually  by  fomites. 
But  we  know  that  germs  of  the  former  class  may  be  trans- 
mitted by  air,  water,  food,  etc.,  and  those  of  the  latter  by 
personal  contact,  though  the  reverse  is  what  usually 
happens  in  the  respective  cases.  Occasionally  disease 
occurs  also  by  inoculation,  the  exciting  organisms  being 
introduced  into  the  body  either  accidentally  or  intention- 
ally through  some  wound  in  the  protecting  skin  or  mucous 
membrane.  The  term  zymotic  was  formerly  applied  to 
those  diseases  occurring  in  epidemics,  and  which  were 
supposed  to  be  due  to  fermentative  processes:  if  used  at 
all,  it  should  be  given  to  any  disease  due  to  a  living 
germ.  The  term  specific  should  only  be  given  to  those 
maladies  which  have  a  specific  origin — i.  e.,  which  have 
been  proved  to  be  due  to  a  single  and  particular  organism. 

In  this  connection  we  may  define  an  epidemic  as  "an 
outbreak  of  a  communicable  or  infectious  disease  affecting 
a  dozen  or  more  individuals  in  quick  succession  before  the 
recovery  of  the  first  case,  whether  arising  from  a  single 
focus  or  several  foci  in  a  neighborhood."^  An  endemic 
disease  is  one  occurring  more  or  less  constantly  in  a  cer- 
tain locality.  When  an  epidemic  extends  over  a  very 
large  territory,  it  is  said  to  be  pandemic. 

That  all  communicable  diseases  are  due  to  vegetal  germs 
or  kindred  animal  organisms  is  more  than  probable,  and 
while  there  are  some  for  which  this  has  not  been  fully 
proved,  it  is  scarcely  possible  that  any  of  these  may  arise 
from  insanitary  conditions  alone  without  the  presence  of  a 
living  causative  organism. 

The  reasons  for  believing  in  the  germ  theory  are  based 
on  empirical  and  logical  facts  as  well  as  theoretical  hy- 
potheses. Even  if  we  ignore  the  scientific  research  work 
already  done,  it  is  evident  that  that  which  causes  a  disease 

^  Committee  of  American  Public  Health  Association,  1898. 


KOCH'S  POSTULATES  51 

— the  contagium — must,  when  introduced  into  a  susceptible 
person  or  animal,  increase  in  quantity  to  an  enormous 
extent.  Note,  for  instance,  the  large  quantity  of  actively 
virulent  matter  thrown  off  from  a  case  of  smallpox  or 
scarlet  fever,  and  yet  how  very  little  is  required  to  initiate 
an  attack  of  the  disease.  No  lifeless  chemical  substance 
has  the  power  of  being  increased  to  such  an  extent  by 
simply  finding  lodgement  in  a  suitable  medium.  The 
causative  factor  or  contagium,  whatever  it  may  be,  evi- 
dently must  have  life  and  the  power  of  reproduction. 

Moreover,  these  causes  of  disease,  when  freed  from  the 
body,  may  be  carried  long  distances,  and  may  still  retain 
for  months  or  years  their  power  for  harm,  only  waiting 
a  suitable  field  in  which  to  multiply  and  cause  the  same 
malady  as  before.  Such  causes  must  therefore  be  capable 
of  entering  a  state  in  which  vitality  is  latent,  and  in  which 
the  reproductive  functions  are  for  a  time  inactive.  But 
it  is  known  that  the  spores  of  many  bacteria,  and  some- 
times the  bacteria  themselves,  may  be  carried  afar,  kept 
for  long  periods  of  time,  and  even  exposed  to  wide  extremes 
of  temperature,  without  being  killed  or  losing  their  power 
of  reproduction  and  rapid  multiplication.  Again,  we 
know  that  substances  that  are  poisonous  to,  or  that  pre- 
vent the  development  of,  these  bacteria  and  kindred  low 
forms  of  life,  do,  when  properly  used,  prevent  or  remove 
the  danger  of  contagion  and  infection. 

There  is  also  in  the  development  and  progress  of 
infectious  disease  a  direct  analogy  to  the  phenomena  of 
fermentation,  whose  causative  organisms  are  of  the  same 
order  as  these  which  we  are  considering;  the  same  rapid 
multiplication  of  cells  in  suitable  media  at  proper  tem- 
peratures— a  period  of  incubation — and  then  changes 
in  the  infected  body  or  host,  which,  after  going 
on  to  a  certain  extent,  check  the  further  development 
and  multiplication  of  the  organism.  What  it  is  in  the 
containing  medium  that  checks  the  growth  of  the  germ 
we  may  not  be  able  to  determine  a  priori^  but  we  may 
assume  it  to  be  something  hostile  to  the  contagium,  as 


52  BACTERIOLOGY  AND  PARASITOLOGY 

alcohol  above  a  certain  percentage  in  the  fermenting 
medium  is  deterrent  to  the  further  growth  of  the  yeast- 
cell. 

Lastly,  if  the  proof  of  Koch's  postulates  is  essential  to 
the  acceptance  of  a  given  microorganism  as  the  cause  of 
a  given  disease,  we  must  believe,  on  the  other  hand,  that 
a  certain  germ  is  a  cause,  if  not  the  only  one,  of  a  certain 
malady  if  these  postulates  be  proven  with  respect  to  the 
germ  and  malady. 

To  determine  whether  an  organism  is  or  is  not  patho- 
genic it  is  necessary  to  experiment  on  living  animals.  To 
do  this  we  must  use  pure  cultures  of  the  organism  and 
carry  out  all  our  processes,  including  inoculations  and 
autopsies,  under  strictly  antiseptic  precautions.  For 
example,  we  may  examine  microscopically  the  blood  and 
various  tissues  of  a  diseased  animal;  if  bacteria  be  present 
in  any  of  these,  we  make  cultures  from  them,  and  if  more 
than  one  kind  of  bacteria  be  present,  the  various  kinds 
must  be  isolated  and  pure  cultures  made  from  each  kind. 
When  a  pure  culture  is  at  last  obtained,  it  may  be  studied 
both  microscopically  and  as  to  its  characteristics  in  various 
media  and  at  different  temperatures.  Finally,  healthy 
animals  known  to  be  susceptible  to  the  disease  in  question 
are  inoculated  from  the  pure  culture  and,  after  the  period 
of  incubation,  carefully  watched  for  symptoms  of  the  dis- 
ease.' Should  these  manifest  themselves,  the  animal  is 
killed  and  its  blood  and  tissues  carefully  examined  for 
the  inoculated  organisms.  A  similar  study  is  to  be  made 
of  each  species  isolated  from  the  first  animal. 

The  postulates  of  Koch,  which  are  necessary  to  prove 
that  a  germ  is  the  cause  of  a  given  disease,  are:  (1)  The 
microorganism  must  be  found  in  the  blood,  lymph,  or 
tissues  of  a  person  or  animal  sick  or  dead  of  the  disease. 
(2)  The  microorganism  must  be  isolated  from  the  blood, 
lymph,  or  tissues,  and  cultivated  in  suitable  media  out- 
side of  the  animal  body.  These  cultivations  must  be 
carried  on  through  several  generations  until  a  pure  cult- 
ure of  the  germ  is  obtained.  (3)  A  pure  culture  thus 


SEPTICEMIA— TOXEMIA  63 

obtained  must,  when  introduced  into  a  healthy  and  sus- 
ceptible animal,  produce  the  disease  in  question.  (4)  In 
the  inoculated  animal  the  same  organism  must  again  be 
found. 

In  the  case  of  many  diseases  peculiar  to  human  beings 
alone  the  third  condition  must  remain  undetermined  and 
our  chain  of  proof  be  broken,  because  we  should  not 
endanger  human  health  or  life  by  experimental  inoculations. 
But  in  diseases  common  to  man  and  animals  the  experi- 
ments necessary  can  be  completely  carried  out,  and  where 
a  germ  can  be  proved  to  be  the  cause,  according  to  these 
postulates,  of  the  malady  in  animals,  we  can  also  fairly 
conclude  that  it  is  the  cause  of  the  same  disease  in  human 
beings.  The  specific  germs  of  a  number  of  maladies  com- 
mon to  man  and  beast  have  thus  been  determined,  together 
with  those  of  a  large  number  of  affections  peculiar  to 
animals  alone. 

Granting  that  a  certain  organism  be  pathogenic,  infec- 
tion by  it  will  depend  not  only  upon  the  susceptibility  of 
the  animal  or  person  concerned,  but  also  upon  the  method 
of  entrance  into  the  body,  the  number  of  microbes  intro- 
duced and  present,  and  especially  upon  their  degree  of 
virulence.  Thus,  the  tubercle  bacilli  produce  effects  of 
different  character  and  gravity  in  different  tissues,  and  it 
needs  no  argument  to  show  that  while  the  normal  resist- 
ance of  the  body  may  be  all-sufficient  to  overcome  a  few 
vicious  germs  taken  in  with  the  air,  food,  or  drink,  it  may 
be  entirely  inadequate  to  resist  and  may  quickly  succumb 
to  large  numbers  of  the  same  enemy,  especially  if  the 
virulence  of  the  latter  be  enhanced,  as  we  now  know  it 
may  be,  by  various  factors  that  thus  assume  great  sanitary 
importance.  Not  the  least  of  these  are  temperature  and 
nutrient  conditions,  and  change  in  potency  due  to  growth 
and  development  in  certain  animal  or  human  bodies. 

After  infection  or  the  reception  of  the  contagium  by  a 
susceptible  animal  or  person  there  is  a  period  of  incuba- 
tion before  the  manifestation  of  the  characteristic  sympH 
toms  of  the  disease.     This  period  is  variable  according 


54  BACTERIOLOGY  AND  PARASITOLOGY 

to  the  disease  or  kind  of  germ,  and  during  it  the  micro- 
organisms rapidly  increase  in  numbers  and  in  their  conse- 
quent power  for  evil. 

After  the  pathological  process  is  well  under  way  we 
shall  probably  find  one  of  two  conditions  existing,  viz., 
that  "in  which  the  blood  is  the  chief  field  of  activity  of 
the  organisms,"^  and  the  vessels  of  the  victim  are  swarm- 
ing with  the  •  microbes — in  other  words,  a  true  septicemia; 
or  else  one  in  which  "the  poisonous  results  are  not  neces- 
sarily accompanied  by  the  growth  of  organisms  in  the 
tissues,"  these  latter,  in  all  likelihood,  not  extending 
beyond  the  lymphatic  glands  nearest  to  the  point  of  inocu- 
lation— i.  e.,  a  toxemia.  A  good  example  of  the  former 
condition  is  furnished  by  a  case  of  anthrax  or  of  pyemia, 
and  of  the  latter  by  diphtheria.  However,  we  shall  find 
in  either  condition  that  if  we  isolate  the  peculiar  product 
or  toxin  of  the  specific  germ,  either  from  artificial  growths 
upon  or  in  culture-media,  or  from  the  blood  or  tissues  of 
an  animal  sick  or  dead  of  the  disease,  and  inoculate  this 
into  a  susceptible  animal,  the  general  symptoms  and 
results  produced  are  practically  the  same  as  in  an  ordinary 
case  of  the  disease.  This  goes  to  prove  that  the  products 
of  pathogenic  organisms  are  toxic  in  character  and  harm- 
ful to  the  tissues,  either  locally  or  generally;  that  each 
of  these  toxic  products  gives  rise  in  susceptible  animals  to 
characteristic  symptoms  which,  taken  together,  constitute 
a  specific  disease,  and  that  infection  must  be  accordingly 
a  biochemical  and  toxicological  process.  Another  point  to 
note  just  here  is  that  these  toxins  are  apparently  harmful 
to  the  microbes  themselves  whenever  they  exceed  a  cer- 
tain amount,  as  is  shown  by  the  fact  that  most  of  the 
infectious  diseases  are  self-limiting,  and  by  the  cessation 
of  growth  and  even  the  death  of  the  germs  in  the  various 
culture-media  aftier  a  certain  length  of  time.  It  is  but 
fair  to  state,  however,  that  there  are  other  possible  expla- 
nations of  this  latter  phenomenon,  viz.,  an  increase  in  the 

1  Abbott,  loc.  cit. 


IMMUNITY  65 

resistance  of  the  infected  body  to  the  action  of  the  germs 
and  toxins,  or,  as  in  the  case  of  culture-media,  the 
marked  change  in  reaction  caused  by  the  microbial 
products. 

Nothing  that  has  been  said  in  the  foregoing  pages 
should  cause  the  reader  to  infer  that  all  infectious  diseases 
are  caused  solely  by  bacteria.  Although  the  maladies  due 
to  the  latter  have  thus  far  attracted  the  earlier  and  greater 
attention  and  study,  a  number  of  transmissible  affections 
are  now  known  to  be  due  to  animal  organisms,  and  it 
is  probable  that  still  others  will  be  added  to  the  list.  But 
whether  a  disease  be  due  to  bacteria,  protozoa,  or  microbes 
of  a  higher  classification,  the  general  principles  stated 
above  will  serve  to  give  an  understanding  of  their  nature 
and  mode  of  causation. 

Immunity. — Having  thus  obtained  some  knowledge  of 
the  exciting  causes  of  infectious  diseases  and  of  how  they 
act,  one  of  the  most  important  considerations  is  in  relation 
to  the  prevention  of  the  incurrence  of  these  diseases  by  the 
well,  and  to  the  antagonizing  or  checking  of  the  further 
action  of  the  cause  in  those  already  infected.  It  is  well  to 
disinfect  and  to  destroy  disease  germs  whenever  and  wher- 
ever it  is  possible  to  do  so,  and  at  the  same  time  to  prevent 
in  any  manner  their  transference  from  unknown  or  inac- 
cessible sources  to  susceptible  persons,  but  it  is  still  better 
so  to  strengthen  and  fortify  the  human  body  that  the 
microbes,  even  though  received  into  it,  will  be  unable  to 
do  it  harm.  Naturally  our  first  desire  would  be  to  secure  a 
permanent  insusceptibility,  if  this  might  be  had  without 
too  great  risk  or  discomfort;  but  since  this  is  rarely 
possible  with  our  present  knowledge,  we  must  endeavor, 
especially  when  the  danger  of  infection  is  imminent,  to 
secure  the  greatest  possible  immunity  even  though  that 
may  be  only  temporary  or  incomplete.  Occasionally 
we  find  individuals  that  possess  extreme  natural  im- 
munity to  certain  maladies;  observation  shows  that  most 
well  persons  have  fair  protection  in  the  case  of  ordinary 
exposure  to  infectious  matter;  and  further  investigation 


56  BACTERIOLOGY  AND  PARASITOLOGY 

teaches  that  this  protection  is  materially  affected  by  such 
factors  as  one's  state  of  health,  occupation,  age,  or  diet, 
or  by  injuries,  drugs,  fatigue,  exposure  to  heat  or  cold, 
etc.  But  our  desire  is  to  know  how  to  provide  a  positive 
immunity  against  each  infection  and  for  all  persons.  That 
we  have  the  means  of  producing  such  protection  with 
respect  to  one  disease  is  well  shown  by  the  history  of 
vaccination,  and  to  another  by  the  results  obtained  in 
our  army  and  others  in  the  recent  world  war  from  the 
general  inoculation  of  soldiers  against  typhoid  fever; 
and  the  work  of  many  investigators  in  recent  years 
indicates  that  the  promise  of  similar  results  in  regard 
to  many  other  maladies  is  by  no  means  vain.  Certain 
it  is  that  many  human  beings  and  animals  have  been 
rendered  apparently  immune  to  other  fatal  diseases, 
and  the  indications  point  to  the  probability  that  the 
human  race  will  shortly  have  the  same  protection  against 
most  of  the  transmissible  maladies  that  it  now  has 
against  smallpox. 

"At  present  the  chief  successes  of  immunotherapy 
have  to  do  with  the  bacterial  diseases,  but  experiments 
show  that  the  same  principles  prevail  among  the  proto- 
zoan infections,  and  there  is  little  doubt  that  as  our 
knowledge  of  these  maladies  becomes  amplified  the 
benefits  of  immunological  research  will  be  found  to  be 
available  in  them.  It  is  now  universally  admitted  that 
microbes  are  pathogenic  or  disease-producing  by  virtue 
of  certain  poisonous  metabolic  products. 

''These  toxic  products,  embracing  what  have  been  vari- 
ously described  by  different  authors  as  toxins,  toxalbumins, 
and  bacterioproteins,  are  all  of  proteid  nature.  Their 
physiological  effects  vary  greatly  among  themselves,  but 
they  all  have  in  common,  and  together  with  practically 
all  heterologous  proteid  substances,  the  property  of 
stimulating  certain  antagonistic  physiologico-chemical 
reactions  on  the  part  of  higher  organisms,  and  hence  are 
included  in  a  group  of  miscellaneous  character,  to  which 
the  name  antigen  has  in  recent  years  been  applied.     By 


ANTITOXIN  THEORY  57 

antigen,  therefore,  is  meant  any  substance  capable  of 
stimulating  an  antagonistic  reaction  when  introduced 
into  the  body  of  one  of  the  higher  organisms.  The  nature 
of  the  reaction  is,  in  itself,  unimportant,  so  long  as  its 
tendency  is  antagonistic  to  the  antigen."* 

Just  here  it  may  be  well  to  consider  several  theories  that 
have  been  advanced  in  the  attempt  to  explain  the  phenom- 
ena of  immunity.  Of  these,  two  have  been  practically 
disproved,  viz.,  the  exhaustion  theory  of  Pasteur,  which 
was  that  the  pathogenic  germs  in  their  process  of  growth 
in  the  body  removed  some  material  from  the  latter  neces- 
sary to  their  existence;  and  the  diametrically  opposite 
retention  theory  of  Chauveau,  which  was  that  the  germs 
produced  some  substance  which  gave  immunity  as  long  as 
it  was  retained  in  the  tissues.  On  the  other  hand  the 
phagocytosis  theory  of  Metchnikoff  and  the  humoral  theory 
of  Biichner  have  been  practically  established  if  considered 
as  being  duly  qualified  by  the  results  of  the  research  of 
later  years. 

The  phagocytosis  theory  is,  that  "immunity  against 
infection  is  essentially  a  matter  between  the  invading 
bacteria  on  the  one  hand  and  the  leucocytes  of  the  tissues 
on  the  other;  that  during  the  first  attack  of  the  disease 
the  white  blood-corpuscles  gain  a  tolerance  to  the  poisons 
of  the  bacteria,  and  so  are  able  to  resist  the  next  incursions 
of  the  enemy  and  to  attack  and  destroy  the  latter,"  the 
fact  that  they  really  ingest  and  digest  the  latter  being 
readily  demonstrable  by  the  microscope. 

Biichner  has  apparently  shown  that  the  blood-plasma, 
especially  that  of  immune  animals,  is  bactericidal  to  many 
virulent  germs,  and  he  attributed  this  effect  to  the  pres- 
ence in  the  fluid  of  certain  proteid  substances  akin  to 
globulin.  These  he  termed  alexins^  from  a  Greek  word 
meaning  to  protect.  Further,  he  believed  that  they  act 
chemically  in  causing  death  of  the  disease  germs,  and 
that  the  increased  amount  of  alexins  in  the  blood  of  those 

»  McFarland  in  Modern  Clinical  Medicine,  Wilson  and  Salinger,  1910, 
pp.  909  and  910. 


58  BACTERIOLOGY  AND  PARASITOLOGY 

who  have  acquired  immunity  is  brought  about  by  a  stimu- 
lation or  "reactive  change"  in  certain  cells  due  to  the 
presence  of  the  bacteria  or  their  products.  Moreover,  this 
humoral  theory  serves  to  account  for  the  natural  immu- 
nity possessed  by  some  individuals  and  animals,  their 
body-juices  presumably  containing,  through  some  cause 
or  other,  an  extra  quantity  of  the  protective  pro- 
teids. 

But  an  essential  factor  in  securing  immunity  is  the 
power  of  the  body  to  resist  or  endure  the  poisons  produced 
by  the  disease  germs,  something  fully  as  important  as  its 
ability  to  destroy  the  infecting  organisms.  Consequently 
there  is  another  theory — that  of  the  antitoxins — which, 
in  view  of  recent  developments  and  the  fact  that  it 
is  capable  of  immediate  practical  application,  is  one  of 
the  most  important  thus  far  proposed.  It  is  well  known 
that  the  human  system  has  the  power  of  tolerating 
or  accommodating  itself  to  the  action  of  almost  any 
toxic  substance — provided  the  latter  be  administered  at 
first  in  sufficiently  minute  doses  and  then  gradually 
increased — until  it  can  in  time  withstand  quantities  that 
would  quickly  prove  fatal  to  one  unaccustomed  to  the 
poison.  Ehrlich  has  further  shown  that  with  the  toxic 
alkaloids  of  certain  higher  plants,  after  a  certain  degree 
of  tolerance  is  attained  the  administration  of  the  drug  may 
be  much  more  rapidly  increased,  and  that  while  up  to  this 
point  no  apparent  change  occurs  in  the  body-fluids,  now, 
when  the  tolerance  becomes  so  much  increased,  a  new 
substance  is  produced  in  the  blood  which  is  capable  of 
neutralizing  the  poison  in  not  only  the  person  or  animal 
under  experimentation,  but  also  in  others  into  whom  it 
may  be  introduced.  Further  investigations  have  shown 
that  this  same  production  of  antidotal  or  antagonizing 
substances  may  be  brought  about  by  the  slow  adminis- 
tration of  the  toxins  of  pathogenic  bacteria — something 
not  hard  to  understand  when  we  remember  that  the 
bacterial  toxins  are  just  as  much  the  products  of  plant-life 
as  are  the  alkaloids  that  Ehrlich  used,  and  very  much 


EHRLICWS  LATERAL  CHAIN  THEORY  59 

like  the  latter  in  composition.  On  the  other  hand,  the 
antitoxins,  as  the  substances  antidotal  to  the  toxins  are 
called,  have  been  found  to  be  albuminoid  in  character 
and  similar  in  composition  to  the  nucleins.  In  fact, 
attempts  have  been  made  to  employ  the  latter  in  place 
of  or  in  conjunction  with  the  antitoxins,  with  results 
that  have  not  been  altogether  without  success. 

Much  credit  must  be  given  to  the  labors  of  Behring, 
Roux,  Kitasato,  Haffkine,  and  others  for  the  development 
of  practical  methods  of  using  the  antitoxins,  methods 
which  are  now  recognized  as  eminently  proper  and  even 
superior  to  any  others  in  the  treatment  of  some  of  the 
most  virulent  diseases.  The  great  reduction  in  the  mor- 
tality from  one  disease  alone — diphtheria — already  at- 
tained through  the  application  of  this  treatment  almost 
exceeds  expectation  and  belief,  and  the  results  with 
respect  to  tetanus,  cholera  and  other  deadly  maladies 
have  been  likewise  brilliant  and  add  further  glory  to  this 
new  science  of  bacteriology. 

More  recently  Wright  has  shown  that  the  blood  contains 
certain  substances  which  can  so  affect  disease-producing 
bacteria  that  the  leucocytes  will  more  readily  destroy 
them  by  phagocytosis.  These  substances,  which  he  calls 
opsonins,  vary  not  only  in  quantity  in  different  persons, 
but  apparently  also  in  quality,  there  being  probably  a 
specific  opsonin  for  each  kind  of  pathogenic  organism. 
Moreover,  it  has  been  found  that  in  many  cases  the 
amount  of  influence  of  a  given  opsonin  can  be  increased 
in  the  blood  by  appropriate  inoculation  of  sterilized  bac- 
teria of  its  particular  kind;  and,  secondly,  that  by  deter- 
mining a  patient's  opsonic  index  for  a  particular  disease 
we  can  approximately  estimate  his  power  of  resistance  or 
degree  of  immunity  to  that  disease.  The  opsonic  index 
of  an  individual  is  the  ratio  between  the  phagocytic  power 
of  a  certain  number  of  leucocytes — as  indicated  by  the 
number  of  bacteria  taken  up  in  a  given  time  when  acted 
upon  by  a  unit  of  his  serum — and  the  power  of  the  same 
number  of  the  same  kind  of  leucocytes  when  the  bacteria 


60  BACTERIOLOGY  AND  PARASITOLOGY 

are  acted  upon  by  a  unit  of  serum  from  a  normal  and 
healthy  person. 

To  some  it  may  seem  that  either  the  humoral  or  the 
antitoxin  theory  is  identical  with  the  discarded  retention 
theory  of  Chauveau;  but  it  should  be  noted  that  accord- 
ing to  the  latter  the  invading  microbes  themselves  produce 
the  antidote  or  antagonizing  substance,  while  Biichner's 
theory  attributes  this  production  to  the  integral  cells  of  the 
body,  which  furnish  the  alexins  normally  in  minute  quan- 
tities to  the  blood,  and  asserts  that  the  latter  are  germicidal 
to  the  bacteria  themselves;  and,  on  the  other  hand,  the 
antitoxins,  though  produced  like  the  alexins  by  body-cells, 
probably  act  chemically  in  neutralizing  the  bacterial 
poisons,  and  are  dependent  upon  the  prior  presence  in  the 
body  of  the  toxins,  being  a  result  of  its  acquired  tolerance 
to  the  latter.  With  alexins  or  antitoxins  it  is  evident 
that  the  immunity  will  last  only  so  long  as  these  sub- 
stances remain  unchanged  in  the  blood. 

However,  there  is  no  reason  why  the  phagocytosis, 
humoral,  antitoxin,  and  opsonin  theories  should  not  mu- 
tually support  rather  than  tend  to  discredit  one  another. 
There  seems  to  be  good  evidence  of  the  phenomena  upon 
which  each  of  them  is  based,  and  even  with  our  present 
incomplete  knowledge  of  the  blood  and  its  component 
parts,  it  is  not  difficult  to  conceive  that  while  the  alexins, 
and  later  the  antitoxins  and  opsonins  protect  the  leuco- 
cytes by  weakening  the  vitality  of  the  microbes  and 
neutralizing  their  products,  the  leucocytes  thus  guarded 
and  in  full  vigor  attack  and  make  way  with  the  bacteria, 
which  have  lost  their  power  for  evil.  In  other  words,  if 
the  production  of  the  toxins  of  an  infectious  malady  is 
not  too  rapid,  all  four  of  these  agents  may  combine  to 
overcome  the  enemy,  and  not  only  to  limit  the  disease, 
but  also  to  give  subsequent  immunity  for  a  more  or  less 
prolonged  period. 

Much  consideration  has  been  given  to  the  so-called 
lateral  chain  theory  of  immunity  suggested  by  Ehrlich 
in  1897,  since  it  serves  better  than  anything  else  to  aid 


EHRLICH'S  LATERAL  CHAIN  THEORY  61 

in  the  solution  of  many  of  the  problems  of  this  abstruse 
subject.  It  is  primarily  dependent  upon  the  well-known 
fact  that  many  poisons,  including  the  bacterial  and  similar 
toxins,  have  a  specific  attraction  toward  and  action  upon 
certain  cells  of  the  body.  Ehrlich  assumes  an  extremely 
complicated  cell  protoplasm  with  many  affinities  for 
combination  with  external  substances.  These  affinities 
may  be  hypothetically  and  graphically  represented  as 
slight  protoplasmic  protrusions  on  the  contour  of  the 
cell-wall,  and  these  affinities  thus  materialized  he  terms 
"lateral  chains"  or  receptors.  Now  according  to  their 
particular  and  respective  affinities  the  receptors  attract 
to  themselves  the  various  molecular  food  particles  that 
the  cell  needs,  it  being  possible,  however,  for  one  receptor 
to  have  an  affinity  for  several  kinds  of  molecules.  Such 
molecules  capable  of  attraction  and  combination  with  the 
receptors  are  termed  "  haptophores."  Accordingly,  hapto- 
phores  of  a  poisonous  nature  that  have  either  entered 
or  been  created  in  the  body  may  combine  with  certain 
receptors  of  a  given  cell,  and  if  of  sufficient  number  and 
virulence  may  altogether  check  the  nutrition  of  and  destroy 
the  cell;  but  if  not  sufficient  in  number  and  toxicity,  the 
irritation  caused  by  the  harmful  haptophores  only  stimu- 
lates the  cell  protoplasm  to  the  formation  of  new  receptors 
of  that  particular  kind  in  order  that  its  nutrition  and 
function  may  be  maintained;  and  it  is  conceivable  that 
through  continued  or  repeated  irritation  the  cell  may 
create  many  more  receptors  than  it  needs,  which  may 
subsequently  be  separated  from  it  and  thrown  off  mto 
the  surrounding  fluids  and  spaces  of  the  body  as  par- 
ticulate bits  of  a  definite  chemical  substance  with  its 
own  specific  affinities  and  properties.  Eventually,  then, 
there  may  be  prepared  enough  specific  and  extra  recep- 
tors, either  attached  to  or  dissociated  from  the  cells,  to 
attract  and  unite  with  all  the  toxic  haptophores  likely 
to  be  present  in  the  body  fluids,  now  or  later,  so  that  the 
cells  are  no  longer  unduly  irritated,  but  perform  their 
functions  in  a  normal  manner.    So,  also,  cells  primarily 


62  BACTERIOLOGY  AND  PARASITOLOGY 

lacking  the  appropriate  receptors  are  immune  against 
the  molecules  of  a  given  poison. 

EhrHch's  theory  goes  further,  and,  taking  into  consider- 
ation the  known  production  in  the  animal  body  under 
stimulation  by  particular  foreign  and  harmful  cells,  such 
as  bacteria,  of  specific  substances  capable  of  dissolving  and 
destroying  the  invading  cells,  assumes  the  production  of 
linking  molecules  or  amboceptors  that  will  bring  into  contact 
and  union  the  solvent  or  lysin  and  the  particular  cells 
which  it  is  to  destroy. 

Thus  we  can  appreciate  the  identity  of  the  receptors 
and  antitoxins,  and  that  the  lysins  just  mentioned  corre- 
spond to  the  alexins  of  Biichner. 

'*  Acquired  immunity  depends  upon  the  regeneration  of 
receptors  to  compensate  for  those  thrown  out  of  service  by 
union  with  useless  haptophores.  The  increasing  immunity 
characterizing  immunization  depends  upon  the  regenera- 
tion of  an  unlimited  number  of  receptors,  so  that  the  cell 
can  provide  for  the  ever-increasing  number  of  haptophores 
brought  to  it  and  still  have  enough  receptors  remaining 
to  carry  on  its  own  nutrition."^ 

MacFarland  has  prepared  the  following  scheme  to  show 
the  present  state  of  knowledge  regarding  immunotherapy, 
its  purposes  and  possibilities.^ 

IMMUNOTHERAPY. 

I.  Prophylaxis. 

1.  Immunity  Induced  Before  Exposure  to  Infection. 

A.  Active  Immunity. 

a.  By  inducing  a  mild  attack  1    y  r  Tr     •  i  n 

r  xi,    J-  u    ^i,  r       Inocula-        f  Variola,      yellow 

of  the  disease  by  the  use  of  ^^^^    i      ^^^^^ 

a  carefully  selected  virus.      I  •    >.  • 


By  the  employment  of  a  J 
much-modified  virus. 


Variola. 


Chicken  cholera, 
anthrax,  quar- 
ter evil,  cholera, 
plague,  typhoid. 


( Jenner) . 

Vaccination 

( Micro  bination) 

(Pasteur). 

B.  Passive  Immunity. 

1.  By  injection  of  antitoxic  1   Antitox-        (  Diphtheria,  teta 
serum.  /  ination.  \     nus. 

1  Medicine,  June,  1903,  p.  450. 

*  Modern  Clinical  Medicine,  Wilson  and  Salinger,  1910,  p.  918. 


IMMUNOTHERAPY 


63 


2.  Immunity  Induced  After  Exposure  to  Infection  and  During 
THE  Incubation  Period  of  the  Disease. 
1.  By    the    employment 


of  comminuted  tissue 
containing  the  essen- 
tial cause  of  the  dis- 
ease in  an  attenuated 
form. 


Microbina- 

TION 


-} 


Rabies. 


II.  Treatment. 

1.  By  Producing  Active  Immunity. 
A.  By  Aiding  the  Bacteria-destroying  Mechanism. 


a.  By  employing  killed  or 
modified  cultures  to  excite 
phagocytosis  through  in- 
crease of  opsonins,  etc. 


Microbina- 

TION. 


B.  By  Aiding  the  Toxin-enduring  Powers, 
b.  By   stimulating   antibody  ] 

formation       during       the  I     Toxina- 
course  of  a  prolonged  in-  f  tion. 

fection.  I 


Acne,  furuncle, 
carbuncle,  chro- 
nic suppuration, 
chronic  gonor- 
rhea, typhoid, 
Malta  fever,  tu- 
berculosis. 


Tuberculosis, 
lepra. 


2.  By  Producing  Passive  Immunity. 


A.  By  injecting  antitoxic  serum 
to  neutralize  toxins  produced 
in  the  course  of  the  infections. 


B.  By  injecting  antimicrobic 
serum  to  aid  in  the  destruc- 
tion of  the  microbes  through 
the  action  of  the  specific 
amboceptors. 


Antitoxi  - 

NATION. 


Antimicro- 
bination. 


Diphtheria,  teta- 
nus,    snake-bite, 
hay-fever,  plague 
tuberculosis, 
lepra. 

Cerebrospinal  fe~ 
ver,  gonorrhcea* 
plague,  dysen- 
tery, pneumo- 
nia, erysipelas, 
scarlet  fever, 
puerperal  fever, 
typhoid,  anthrax 
tuberculosis. 


Method  of  Preparing  Diphtheria  Antitoxin.  —  Within 
a  comparatively  short  space  of  time  the  antitoxins 
have  been  discovered,  tried,  and  practically  adopted  by 
the  medical  profession  of  the  civilized  world  as  a  safe  and 
efficient  means  for  the  prevention  or  the  alleviation  and 


64 


BACTERIOLOGY  AND  PARASITOLOGY 


cure  of  several  of  our  most  dreaded  diseases.  A  short 
account  of  the  usual  method  of  preparing  the  antitoxin  of 
diphtheria  will  therefore  probably  not  be  uninteresting. 
In  the  first  place,  it  is  necessary  that  the  toxin  of  the 
disease  should  be  produced,  which  is  commonly  done 


Fig.  11. — Filter  for  removing  bacteria  from  fluid  culture-media. 

by  growing  the  specific  organism  in  peptone-bouillon. 
When  this  has  attained  a  powerful  and  definite  virulence, 
as  determined  by  its  effect  on  small  animals  of  known 
weight,  the  organisms  are  destroyed  by  some  germicide, 
such  as  trikresol,  or  more  commonly  are  removed  by 
careful    filtration    from    the    bouillon    which    holds    the 


Fig.  12. — Roux  aseptic  hypodermic  syringe  for  administering  antitoxin. 


toxin  in  solution.  A  sniall  quantity,  say  0.1  c.c.  of  the 
filtered  bouillon  is  then  injected  into  a  large  animal,  such 
as  the  horse,  which  should  be  in  good  health,  and  which 
preferably  should  have  been  tested  previously  by  inocula- 
tions of  tuberculin  and  mallein  to  eliminate  the  possibility 


PREPARATION  OF  ANTITOXIN  65 

of  the  presence  of  tuberculosis  or  glanders.  After  the 
injection  of  the  toxin,  the  animal  manifests  for  a  few 
days  the  disturbances  peculiar  to  the  disease  in  question 
but  usually  in  a  minor  degree,  since  the  dose  was  pur- 
posely quite  small  in  proportion  to  its  weight.  As  soon 
as  recovery  is  evident  another  inoculation  of  an  increased 
dose  is  made,  and  so  on  until  experiment  shows  that 
the  animal  can  withstand  practically  an  unlimited 
quantity  of  the  toxic  bouillon,  and  certainly  an  amount 
which  w^ould  have  been  quickly  fatal  before  the 
first  inoculation.  This  is  evidence  that  the  antitoxin 
has  been  produced  and  that  it  exists  in  approximately 
sufficient  degree  in  the  blood-serum,  but  positive  con- 
firmation is  secured  by  introducing  a  little  of  the  horse's 
blood  into  a  guinea-pig  or  other  small  animal  that  has 
received  a  surely  fatal  dose  of  the  toxin  bouillon.  If  it  sur- 
vives, a  quantity  of  blood  is  then  drawn  with  the  strictest 
antiseptic  precautions  into  sterile  flasks  from  the  jugular 
or  other  large  vein  of  the  horse,  the  latter  returned  to 
its  quarters,  and  the  blood  set  aside  in  a  cool  place  to 
coagulate.  This  done,  the  clear  serum  containing  the  anti- 
toxin is  drawn  off  and  to  it  is  added  a  sfhall  quantity  of 
trikresol  or  other  harmless  preservative. 

It  is  now  necessary  to  determine  the  strength  of  the 
serum.  The  fatal  dose  of  toxin  for  guinea-pigs  is  readily 
found  by  experiment.  Behring  therefore  suggested  in 
the  case  of  diphtheria  antitoxin  that  the  immunizing  unit 
be  taken  to  be  1  c.c.  of  a  serum  of  which  0.1  c.c.  would 
prevent  edema  and  death  in  guinea-pigs  when  injected 
simultaneously  with  10  times  the  fatal  dose  of  the  toxin. 
In  other  words,  the  immunizing  unit  was  to  be  sufficient 
to  overcome  100  times  the  amount  of  the  toxin  required 
to  kill  a  guinea-pig.  The  antitoxin  serums  now  adminis- 
tered are,  however,  much  stronger  than  this  normal  serum 
of  Behring's,  the  amount  usually  injected  being  equivalent 
to  from  500  to  5000  or  even  more  immunizing  units,  the 
weaker  strength  being  used  for  immunizing  those  who 
have  not  as  yet  incurred  the  disease. 
5 


66  BACTERIOLOGY  AND  PARASITOLOGY 

Much  depends  upon  the  early  use  of  the  specific  antitoxin 
in  cases  of  diphtheria,  and  probably  also  in  the  other  dis- 
eases for  which  this  method  of  treatment  is  found  valu- 
able, for  it  is  not  to  be  supposed  that  the  remedy  has  any 
power  to  repair  the  organic  lesions  which  have  been  caused 
by  the  action  of  the  powerful  toxins,  and  if  the  latter  are 
permitted  to  act  for  a  considerable  time  before  being 
neutralized  by  the  respective  antitoxins,  fatal  or  incurable 
damage  may  be  done. 

That  the  antitoxin  treatment  is  invaluable  cannot  be 
doubted.  The  statistics  of  Prof.  Welch,  of  Johns  Hopkins 
Hospital,  founded  on  a  very  large  number  of  diphtheria 
cases,  "show  an  apparent  reduction  of  case-mortality  of 
55.8  per  cent.,''  and  where  the  application  was  made  in 
the  first  three  days  of  the  disease  the  mortality  was 
only  8.5  per  cent,  in  over  1100  cases  as  against  a 
mortality  of  30  per  cent,  or  higher  under  former 
methods  of  treatment.  Another  interesting  report  is 
that  of  the  Chicago  Department  of  Health  for  1896. 
In  that  city  in  that  year  there  were  2436  cases 
of  true  diphtheria  verified  bacteriologically.  The  anti- 
toxin was  administered  to  2302  of  these,  with  a  resultant 
mortality  of  only  6.56  per  cent.,  or  151  deaths.  More- 
over, 2016  other  persons  exposed  to  the  disease  were 
inoculated  with  the  antitoxin  in  order  to  immunize  them, 
and  of  these,  only  14  subsequently  contracted  the  malady, 
and  none  died.  Moreover,  the  average  yearly  death-rate 
from  diphtheria  and  croup  in  Chicago  for  the  pre-anti- 
toxin  decade  (1886-1895)  was  140.2  per  100,000  of  popu- 
lation, as  against  41.8  in  the  antitoxin  decade  (1896-1905) 
and  21.7  for  1905.  In  other  words,  notwithstanding  a 
great  increase  in  population,  the  average  yearly  deaths 
from  these  diseases  dropped  from  1423  for  the  first  decade 
to  693  for  the  second,  and  to  433  for  1905.  Further 
comment  seems  unnecessary,  but  the  statistics  of  the 
United  States  Census  already  quoted,  showing  a  reduction 
in  the  death-rate  from  this  disease  from  1890  to  1916 
from  70.1  to  14.5  per  100,000  in  what  now  comprises 


VALUE  OF  ANTITOXIN  TREATMENT  67 

70  per  cent,  of  the  population  of  the  whole  country,  is 
even  more  striking,  especially  as  the  gain  must  be  attrib- 
uted almost  entirely  to  the  adoption  and  use  of  the  anti- 
toxin. The  results  have  been  so  positive,  the  advance  so 
progressive,  and  any  changes  in  the  previous  methods  of 
treatment  of  the  disease  so  slight  as  to  preclude  the  possi- 
bility of  doubt  as  to  the  wisdom  of  employing  it  both  as 
a  remedy  and  as  a  prophylactic. 

The  immunity  secured  by  the  use  of  an  antitoxin  is 
almost  immediate,  an  advantage  often  of  the  greatest 
importance;  but  since  it  is  passive,  the  antitoxin  having 
been  developed  outside  of  the  person  protected,  it  is  more 
or  less  transient,  and  the  inoculation  must  be  repeated  at 
intervals,  or  when  danger  of  new  infection  is  imminent. 
The  same  remarks  apply  to  the  use  of  antimicrobin,  the 
product  resulting  from  the  gradual  introduction  of  the 
bodies  of  killed  bacteria  rather  than  their  toxins  into 
susceptible  and  suitable  animals.  This  latter  gives  rather 
a  bacteriolytic  form  of  immunity,  and  thus  far  is  not  so 
satisfactory  as  that  due  to  antitoxin. 

On  the  other  hand,  immunity  that  is  acquired  actively, 
either  by  accident  or  by  deliberate  experiment,  is  slower 
in  developing,  but  much  more  likely  to  be  permanent.  It 
is  a  result,  as  we  know,  of  most  of  the  spontaneous  infec- 
tious diseases,  though  its  duration  in  some  cases  is  briefer 
than  we  desire.  It  may  also  be  secured  by  prophylactic 
infection  or  by  prophylactic  intoxication.  In  the  former 
we  may  use  virulent  infective  matter  in  much  reduced 
doses  or  quantities,  or  better  and  more  safely  as  far  as 
man  is  concerned,  some  form  of  attenuated  virus  may  be 
employed,  the  infecting  matter  having  been  modified 
by  development  in  animals  of  another  species,  or  by  heat, 
light,  drying,  electricity,  growth  in  unfavorable  media,  etc. 
As  an  illustration,  we  have  the  modern  vaccine  virus 
derived  from  the  cow  which  has  entirely  supplanted  the 
former  direct  inoculation  of  matter  from  the  human  small- 
pox patient.  As  for  prophylactic  intoxication,  we  may 
use  either  the  dead  bodies  of  the  infectious  bacteria,  as 


68  BACTERIOLOGY  AND  PARASITOLOGY 

has  been  done  by  Haffkine  in  his  work  against  plague 
and  cholera,  and  more  recently  in  antityphoid  inocula- 
tion, or  the  products  of  the  organisms  derived  from 
artificial  cultures,  as  indicated  in  describing  the  produc- 
tion of  antitoxin.  Various  factors,  some  still  unsettled, 
must  determine  the  advisability  of  the  use  in  a  given  case 
of  one  or  another  of  the  above  methods;  but  it  must  be 
remembered  in  regard  to  actively  acquired  immunity,  that 
not  only  is  it  at  times  too  slow  in  development  to  be  of 
value  after  infection  has  occurred,  but  also  that  "the  in- 
troduction of  toxins  or  bacterial  proteids  after  the  onset 
of  the  disease  may  be  not  merely  useless,  but  actually 
harmful  by  adding  to  the  sum  total  of  toxic  material 
against  which  the  tissues  struggle." 

Nevertheless,  experience  will  continue  to  show  that 
whether  one  or  all  of  these  methods  of  securing  immunity 
may  be  employed  or  whether  others  by  which  the  body 
can  protect  itself  may  be  discovered,  sanitation  and  a  con- 
dition of  perfect  health  throughout  the  system  are  of  the 
utmost  importance  in  warding  off  attacks  of  or  in  securing 
immunity  from  any  of  the  pathogenic  organisms,  and  in 
withstanding  their  ravages  should  disease  be  incurred. 
A  sound  body  therefore  is  a  most  vitally  active  and  not 
simply  a  passive  agent  for  the  prevention  of  such  diseases. 


CHAPTER  IIJ. 
THE  ATMOSPHERE— AHl. 

The  composition  of  the  atmosphere  surrounding  the 
earth  is  remarkably  uniform.  It  is  practically  always 
the  same  everywhere,  provided  no  obstacle  be  interposed 
to  the  action  of  those  natural  forces  by  which  this  uni- 
formity is  maintained.  This  atmosphere  is  estimated  to 
be  about  forty  miles  in  depth,  and  its  weight-pressure, 
of  which  we  have  a  visible  manifestation  in  the  action  of 
the  barometer,  upon  the  total  surface  of  the  adult  human 
body  is  equivalent  to  that  of  about  fourteen  tons.  Any 
considerable  variation  in  this  pressure  may  give  rise  to 
disturbances  of  health  more  or  less  serious,  such  as  the 
cardiac  derangements  and  "mountain  sickness"  experi- 
enced by  strangers  visiting  high  altitudes  and  by  avia- 
tors, or  the  "caisson  disease"  of  those  who  work  in 
a  compressed  atmosphere.  In  fact,  it  is  not  improbable 
that  some  of  the  vague  disturbances  of  comfort  to  which 
a  large  class  of  persons  are  subject  during  changes  of  the 
weather  will  hereafter  be  found  to  be  due  to  the  marked 
variations  in  this  pressure  at  such  times. 

The  average  composition  of  the  air  in  its  normal  state 
is  about  as  follows:  oxygen,  20.96  per  cent,  by  volume; 
nitrogen  and  argon,  79  per  cent.;  carbon  dioxide,  0.04 
per  cent.;  aqueous  vapor,  varying  in  amount  with  the 
temperature  and  other  conditions;  a  trace  of  ammonia, 
and  a  variable  amount  of  ozone,  organic  matter,  sodium 
salts,  etc.  The  variation  in  the  percentage  of  oxygen  may 
be  from  20.87  in  towns  to  20.98  in  pure  mountain  air  or 
far  out  at  sea;  in  the  percentage  of  carbon  dioxide,  from 
0.02  to  0.05.    So  far  as  we  know  at  present,  the  nitrogen 

(69) 


70 


THE  ATMOSPHERE— AIR 


variation  is  almost  infinitesimal.  The  air  is  a  mechanical, 
not  a  chemical  mixture,  and  there  is  always  some  change 
taking  place  in  the  proportions  of  the  various  constituents. 
However,  the  mixture  is  maintained  in  its  wonderful 
uniformity  by  the  interdependent  action  of  plants  and  ani- 


M.M.Hg. 

ALTITUDE 
6000  FT.             14130  FT.        ui30  ft.  (sh'h^s.) 

PULSE 
RATE 

100 

135 

, 

■ 

/     ■ 

95 

/ 

/ 

90 

130 

.y 

85 

o^"' 

..'' 

80 

125 

V 

75 

\ 

120 

N^^^ 

^ 

^ 

115 

■ 

PULSE  RATE- 


BLOOD  PRESSURE- 


Fig.  13. — Physiological  changes  due  to  rapid  change  in  altitude. 
Average  blood-pressure  and  pulse-rate  of  22  young  men.  Adapted  from 
papers  of  Drs.  Gardner  and  Hoagland  in  the  Transactions  of  the  Ameri- 
can Climatological  Association,  1905,  xxi,  85. 


mals,  and  by  the  diffusion  of  gases,  the  law  of  which  is 
that  "  a  gas  expands  into  a  space  in  which  there  is  another 
gas  as  freely  and  as  rapidly  as  if  there  were  a  vacuum." 
Though  this  agency,  like  the  other,  is  continually  operat- 
ing, its  results  are  greatly  facilitated  by  adventitious  air- 


COMPOSITION  OF  AIR  71 

currents  and  by  the  application  of  heat.  When  a  gas  is 
thus  diffused,  it  will  not  separate  again  from  the  others 
under  ordinary  circumstances. 

Oxygen  is  the  most  important  of  the  above  constituents. 
It  supports  all  animal  life;  oxidizes,  destroys,  and  renders 
harmless  organic  impurities,  and  by  oxygenating  the  blood 
and  oxidizing  the  food  for  our  tissues  gives  heat  and 
energy,  the  vital  source  of  all  our  thoughts  and  actions. 
The  supply  to  the  atmosphere  is  constantly  maintained  by 
the  higher  plant-life,  which  decomposes  carbon  dioxide 
and  gives  off  oxygen  to  the  air.  In  man  the  greatest 
limit  of  life  without  oxygen  or  air  is  about  four  minutes. 
A  decrease  in  the  proportion  of  oxygen  in  the  air  does 
not  manifest  itself  by  untoward  symptoms  in  the  human 
body  until  there  is  less  than  13  per  cent,  by  volume;  then 
as  it  falls  lower  and  lower  the  respirations  become  slower, 
deeper,  and  more  difficult,  less  oxygen  is  absorbed  by  the 
blood,  and  there  follow  dyspnea,  asphyxia,  and  death. 
This  may  occur  within  a  short  time  when  the  percentage 
goes  below  8  per  cent.,  and  fatal  asphyxia  supervenes  very 
rapidly  when  there  is  as  little  as  3  per  cent,  of  oxygen. 

Some  very  interesting  investigations  made  by  the 
Medical  Research  Board  of  the  Air  Service  of  the  U.  S. 
Army  in  1918  show  that  "in  normal  men  characteristic 
alterations  of  function  begin  even  with  a  slight  lower- 
ing of  the  oxygen  tension,"  and  that  "for  all  persons 
there  are  limits  beyond  which  the  body  cannot  com- 
pensate. In  this  respect  there  are  the  widest  individual 
variations,  forming  a  scale  from  the  man  with  a  weak 
heart,  who  can  withstand  scarcely  any  reduction  of 
oxygen,  up  to  the  man  whose  respiration  and  circulation 
are  of  such  adaptability  and  power  that  he  can  go  to 
25,000  feet  and  yet  for  a  time  be  virtually  normal.  The 
strain  imposed  by  altitude  is  closely  similar  to  that 
induced  by  extreme  physical  exertion.  In  botli  condi- 
tions oxygen  deficiency  occurs,  but  at  altitudes  and  in  an 
aeroplane  the  effects  are  the  more  subtle  and  dangerous 
because  of  the  lack  of  stimulation  to  breathing  and  other 


72  THE  ATMOSPHERE— AIR 

functions  that  the  increased  carbon  dioxide  production 
affords  during  muscular  exertion."^  The  same  inves- 
tigations show  that  while  the  rate  of  heart-beat  has  been 
found  to  accelerate  in  a  few  men  at  17.5  per  cent,  of 
oxygen,  corresponding  to  an  altitude  of  5000  feet,  only 
13  per  cent,  of  those  examined  reacted  in  this  way  until 
the  oxygen  was  reduced  to  less  than  15  per  cent.,  and 
that  "  the  pulse-pressure  remains  fairly  constant  in  most 
men  until  the  oxygen  has  fallen  to  between  12  and  9  per 
cent,  (from  14,500  to  22,000  feet),  after  which  it  increases 
in  amount  during  the  further  reduction  in  oxygen.'^ 

The  main  function  of  the  nitrogen  of  the  atmosphere 
seems  to  be  to  act  as  a  diluent  and  to  prevent  the  too 
energetic  action  of  the  oxygen.  We  know  now,  however, 
that  at  least  one  family  of  plants-^the  leguminosse — is 
able,  by  the  aid  of  certain  bacteria,  to  take  nitrogen  almost 
directly  from  the  air  and  to  store  it  in  the  form  of  pro- 
teids  for  future  use  as  a  food  for  animals.  The  ammonia 
ever  present  in  the  air  is  also  a  source  of  nitrogen  food  for 
some  plants. 

The  gaseous  element  argon,  discovered  in  1894  by 
Lord  Rayleigh  and  Prof.  Ramsay,  comprises  about  1 
per  cent,  of  what  was  previously  considered  atmospheric 
nitrogen.  Thus  far  little  is  known  concerning  it  except 
that  its  atomic  weight  is  probably  somewhat  less  than  40, 
its  density  about  20,  and  that  it  is  very  inert,  though 
Berthelot  has  succeeded  in  making  it  combine  with  nas- 
cent vapors  of  benzene  under  the  influence  of  an  elec- 
trical discharge.  That  it  is  a  constant  component  of  the 
atmosphere  for  some  definite  purpose  is  more  than  prob- 
able, but  what  this  purpose  may  be  is  as  yet  unknown. 

The  carbon  dioxide^  present  in  the  atmosphere  is  of  no 
direct  use  to  animals,  but  is  essential  to  the  support  of 
vegetable  life,  furnishing  part  of  the  carbon  necessary  for 

^  Medical  Studies  in  Aviation,  Jour.  Am.  Med.  Assn.,  October  26,  1918, 
No.  17,  vol.  Ixxi. 

2  Carbon  dioxide  =  carbonic  acid  gas  =  carbonic  anhydride  =  CO2. 
Carbon  monoxide  =  carbonous  oxide  =  CO. 


CARBON  DIOXIDE  IN  AIR  73 

the  formation  of  the  carbohydrates  and  proteids,  which 
are,  next  to  water,  the  main  constituents  of  plants.  The 
proportion  of  carbon  dioxide  in  the  out-door  air  varies 
somewhat  from  time  to  time,  owing  to  the  changing 
conditions.  It  is  washed  out  of  the  air  by  rain,  and  there 
is  therefore  less  after  a  heavy  storm;  plants  absorb  it 
by  day,  and  some  give  off  a  slight  quantity  by  night;  the 
strata  of  the  atmosphere  near  the  ground  receive  an  excess 
of  it  from  the  soil-air;  it  is  a  constant  product  of  combus- 
tion and  of  the  decomposition  of  organic  matter  by  sapro- 
phytic bacteria,  etc.  Though  heavier  than  air,  it  is  com- 
paratively evenly  distributed  through  the  atmosphere  by 
the  force  of  diffusion. 

The  normal  proportion  in  the  atmosphere  varies  from 
0.02  per  cent,  to  0.05  per  cent.,  but  we  may  take  the 
average  to  be  about  0.04  per  cent.  Should,  however,  any 
important  tests  of  the  amount  in-doors  be  required,  the 
percentage  in  the  out-door  air  at  that  particular  time  and 
place  should  for  the  sake  of  accuracy  also  be  determined. 
Within  the  limits  just  given,  the  carbon  dioxide  cannot  be 
considered  as  an  impurity  of  the  atmosphere,  for  it  is  ever 
present  in  the  air,  and  is  as  necessary  to  plant-life  as 
oxygen  is  to  animals.  It  is  derived  from  the  combus- 
tion of  carbonaceous  materials,  from  the  exhalations  and 
excretions  of  animals  and  men,  and,  as  was  indicated,  in 
large  measure  by  the  action  of  the  saprophytic  bacteria 
and  also  of  the  budding  fungi  upon  organic  matter. 
Moreover,  any  excess  above  the  hormal  percentage  as 
given  is  to  be  regarded  not  so  much  an  impurity  of 
the  atmosphere  as  an  indication  that  certain  processes 
are  at  work,  which  by  their  other  products  may  make 
the  air  impure  and  unsafe  for  human  use. 

The  amount  of  aqueous  vapor  in  the  atmosphere  varies 
from  time  to  time  because  the  factors  governing  it — con- 
densation and  evaporation — are  continuously  in  action, 
these  depending,  of  course,  mainly  upon  the  continual 
variations  in  temperature.  There  is  probably  never  a 
perfectly  dry  air  unless  it  is  made  so  artificially,  and 


74  THE  ATMOSPHERE— AIR 

precipitation  occurs  the  moment  complete  saturation  is 
reached.  The  usual  range  of  relative  humidity  is  probably 
from  30  to  100  per  cent.,  this  being  equivalent,  according 
to  the  temperature,  to  a  water-content  of  from  1  to  12  or 
14  grains  to  the  cubic  foot  of  air.  The  most  satisfactory 
proportion  for  health  has  not  been  experimentally  deter- 
mined, but  is  generally  considered  to  be  from  40  to  70 
per  cent,  when  the  temperature  is  moderate.^ 

In  the  outdoor  air  there  is  at  least  a  trace  of  ammonia 
either  free  or  combined,  a  small  amount  of  the  salts  of 
sodium  (especially  near  the  sea)  and  of  other  metals, 
^nd  a  trace  of  organic  matter.  This  last  is  part  of  the 
animal  and  vegetable  debris  of  the  earth;  when  above 
a  trace,  it  is  to  be  treated  as  an  impurity,  as  should  any 
excess  of  ammonia. 

Minute  particles  of  innumerable  substances  are  being 
constantly  thrown  off  into  the  atmosphere,  and  it  is 
only  the  unceasing  action  of  nature's  purifying  powers 
that  keeps  the  proportion  within  the  limits  of  safety  to 
the  human  race.  Solid  particles,  lifted  up  by  the  winds, 
fall  to  the  earth  again,  or,  if  organic,  are  partially  oxi- 
dized and  decomposed  by  the  oxygen  and  ozone.  The 
gases  are  diluted  and  diffused  so  as  to  be  no  longer  harm- 
ful, or  are  decomposed,  or  are  washed  back  to  the  earth 
by  rain  or  snow.  The  great  volume  of  carbon  dioxide  is 
kept  within  bounds  by  the  action  of  the  vegetable  world. 
The  natural  purifiers  of  the  atmosphere,  therefore,  are 
the  force  of  gravity,  diffusion,  dilution  by  the  air  itself, 
winds,  oxidation,  rain,  and  the  action  of  plant-life;  and 
so  exactly  are  these  adjusted  to  their  work  that  never, 
when  they  have  fair  opportunity  to  act,  does  the  com- 
position of  the  air  vary  much  from  the  normal  for  any 
great  length  of  time. 

The  impurities  in  the  atmosphere  that  are  especially 

1  When  the  temperature  is  upward  of  80°  F.  a  humidity  of  but  little 
more  than  70  per  cent,  may  be  very  uncomfortable  and  depressing  if 
the  air  is  still  and  evaporation  from  the  body  surface  thus  impeded.  A 
breeze  makes  such  humidity  or  even  a  higher  one  less  noticeable. 


ATMOSPHERIC  IMPURITIES  75 

likely  to  have  a  deleterious  influence  upon  health  may  be 
classed  as  follows:  (1)  Suspended  matters.  (2)  Gaseous 
and  semigaseous  substances,  including:  (3)  Those  espe- 
cially due  to  combustion  and  decomposition  processes, 
and  which  are  particularly  likely  to  contaminate  the  air 
of  dwellings  or  inhabited  apartments. 

The  most  important  suspended  matters  are  sand,  dust, 
soot,  pollen  of  various  plants,  microorganisms  of  all 
kinds,  particles  of  epithelia  and  other  excreta  thrown 
off  from  animal  bodies,  and  finely  divided  substances 
characteristic  of  certain  trades  or  industries.  These  may 
do  harm  by  clogging  the  air-vesicles  of  the  lungs  and 
thus  obstructing  respiration,  though  it  is  doubtful  whether 
their  action  is  ever  only  so  mild  or  simple;  by  their 
irritant  action  upon  the  respiratory  passages;^  by  being 
in  themselves  poisonous  or  hostile  to  the  system,  or,  as  in 
the  case  of  microorganisms,  by  the  influence  they  have 
in  the  causation  of  disease.  Disease  germs  may  lodge  in 
the  respiratory  passages  and  do  harm,  or  may  be  swal- 
lowed and  so  cause  maladies,  such  as  typhoid  fever  or 
cholera,  which  primarily  affect  the  digestive  tract. 

It  is,  however,  questionable  whether  pathogenic  organ- 
isms, especially  the  bacteria,  are  commonly  to  be  found 
dissociated  from  other  substances  floating  in  the  air.  Ex- 
periments by  Cornet,  Tyndall  and  others  seem  to  show  that 
such  microbes  are  more  apt  to  be  adherent  to  dust  particles, 
particularly  those  of  organic  nature,  and  it  is  probable 
that  free  bacteria  in  the  out-door  atmosphere  could  not 
long  maintain  their  vitality  deprived  of  nutriment  and 
exposed  to  the  action  of  light  and  oxygen.  Besides, 
they  are  so  quickly  dispersed  and  reduced  in  numbers  in 
any  reasonable  volume  of  unconfined  air  that  the  occa- 
sions must  be  rare  indeed  when  they  could  thus  cause 

1  The  pollen  from  certain  varieties  or  species  of  plants  is  thought  by 
many  to  have  a  specific  influence  in  the  causation  of  hay  fever  and 
similar  ills,  and  there  seems  to  be  no  doubt  that  it  is  frequently  an 
aggravating  and  predisposing  factor  in  the  development  or  course  of 
such  disturbances. 


76  THE  ATMOSPHERE— AIR 

disease.  In-doors,  especially  where  ventilation  is  neg- 
lected, the  case  is  different,  and  there  is  no  doubt  that  the 
air  may  thus  occasionally  become  the  carrier  of  dangerous 
pathogens." 

We  must  also  make  a  distinction  as  to  whether  the 
other  solid  impurities  are  found  in  the  out-door  air  or  in 
enclosed  spaces;  and  if  in  the  latter,  whether  in  healthful 
dwellings,  in  sick-rooms  and  hospitals,  or  in  workshops 
and  factories.  Out-of-doors,  dust,  sand,  soot,  pollen,  waste 
dirt  from  dwellings,  street  refuse,  and  the  remains  of 
plant  and  animal  life  will  predominate;  in-doors  the  par- 
ticles will  be  more  limited  in  variety,  but  not  in  impor- 
tance. Among  them  will  be  epithelial  and  other  cells, 
possibly  pus-corpuscles,  hair,  bits  of  clothing,  food,  etc. 
One  may  also  find  arsenical  or  other  poisonous  dust 
from  wall-paper  or  paint.  In  sick-rooms  and  hospitals 
there  will  probably  be  pus-cells,  mycelia,  bacteria,  etc. 
Mills,  factories,  and  mines  have  their  special  atmospheres 
laden  with  particles  peculiar  to  the  occupation,  which  in 
many  cases  have  a  marked  influence  for  harm  on  the 
health  of  the  workers. 

The  gaseous  and  semigaseous  impurities  of  most  im- 
portance are  not  so  much  those  resulting  from  human 
respiration  and  cutaneous  exhalations,  but  rather  the  prod- 
ucts of  combustion,  peculiar  gases  in  sewer-air  or  soil-air, 
organic  emanations  and  vapors  from  decomposing  animal 
and  vegetable  matter,  and  the  volatile  substances  that 
characterize  the  various  atmospheres  in  and  about  gas- 
works, factories,  and  other  places  of  industry.  Chemically, 
they  may  be  classified  as  the  compounds  of  carbon  and  of 
sulphur  with  oxygen  and  hydrogen,  ammonia  compounds, 
volatilized  minerals  and  mineral  acids,  and  many  gaseous 
and  semigaseous  matters  of  organic  nature  but  indeter- 
minate composition. 

Inasmuch  as  certain  of  these  impurities,  viz.,  human 
exhalations,  combustion-products,  and  not  infrequently 
the  so-called  sewer-gas,  are  particularly  liable  to  be  found 
together  as  contaminants  of  the  atmosphere  of  inhabited 


IMPURITIES  IN  DWELLINGS  77 

rooms  and  dwellings,  it  will  be  advisable  to  consider  them 
in  a  class  by  themselves,  and  to  study  their  effect  upon 
health  both  collectively  and  singly. 

The  volatile  excreta  from  the  body  are  carbon  dioxide, 
aqueous  vapor,  and  a  considerable  amount  of  nitrog- 
enous organic  matter,  to  which  the  term  "crowd- 
poison"  is  sometimes  given.  As  products  of  combustion 
from  the  ordinary  lighting  and  heating  apparatus  of 
dwellings  we  may  have  carbon  dioxide,  carbon  monoxide, 
sulphur  dioxide,  ammonia  (with  possibly  its  sulphide), 
and  aqueous  vapor.  Of  sewer-gas  and  soil-air  we  shall 
speak  later. 

Carbon  dioxide,  contrary  to  the  general  opinion,  cannot 
be  said  to  be  directly  harmful  to  health  in  the  propor- 
tions in  which  it  is  likely  to  be  found  in  any  dwelling 
or  inhabited  apartment.  Although  present  to  the  ex- 
tent of  not  more  than  0.05  per  cent,  in  normal  out-door 
air,  numerous  experiments  indicate  that  both  men  and 
animals  may  inhale  much  larger  proportions  than  this 
without  apparent  harm  provided  the  percentage  of  oxygen 
in  the  air  be  maintained  at  or  above  the  normal;  an 
increase  of  the  carbon  dioxide  from  other  sources  than 
respiration  and  combustion  seems  to  have  no  appreciable 
effect  upon  health  until  it  amounts  to  at  least  1  or  2  per 
cent.,  and  some  men  work  daily  in  atmospheres  contain- 
ing almost  this  amount  as  a  result  of  their  peculiar  occu- 
pations. Dyspnea  does  not  begin  to  occur,  and  then 
only  in  some,  until  the  percentage  goes  above  3  or  4. 
In  quantities  above  these  figures  there  is  much  difference 
of  opinion  as  to  the  effect  of  the  gas  upon  the  human 
economy,  and  the  writer  is  not  aware  that  it  has  ever 
been  determined  just  what  percentage  is  fatal.  Parkes 
states  the  lethal  proportion  to  be  from  5  to  10  per  cent.; 
while  another  authority  states  that  animals  may  be  kept 
for  a  long  time  in  an  atmosphere  in  which  there  is  a  high 
percentage  of  carbon  dioxide  provided  the  percentage 
of  oxygen  be  increased  at  the  same  time.  Hime  says  that 
"  it  may  be  assumed  that  10  or  20  per  cent,  is  a  dangerous 


78  THE  ATMOSPHERE— AIR 

amount"  ;i  but  Wilson^  shows  that  air  having  from  25 
to  30  per  cent,  may  be  inhaled  with  impunity.  It  is 
to  be  understood  that  the  above  percentages  are  all  hy 
volume. 

According  to  his  weight,  an  adult  man  at  rest  absorbs 
from  15  to  18  cubic  feet  of  oxygen  and  exhales  from 
12  to  14  cubic  feet  of  carbon  dioxide  in  twenty-four 
hours.  Reichert^  says:  "The  amount  of  O  varies  from 
600  to  1200  grammes  (15  to  30  cubic  feet)  per  diem,  and 
that  of  CO2  from  700  to  1400  grammes  (12.5  to  25  cubic 
feet) — approximate  averages  being  about  750  grammes 
of  O  and  875  grammes  of  CO2."  According  to  Ott,^ 
"The  amount  of  water  thrown  off  daily  is  about  a  pound; 
of  oxygen  taken  in,  about  a  pound  and  one-half;  and  of 
carbonic  acid  thrown  off,  a  little  more  than  a  pound  and 
one-half."  The  minimum  excretion  per  hour  may  there- 
fore fairly  be  taken  to  be  about  0.7  cubic  foot  of  carbon 
dioxide  for  adult  men  and  0.6  cubic  foot  for  women  or 
for  each  person  of  a  mixed  assemblage.  Now,  granting 
the  presence  of  a  single  adult  occupant,  it  is  evident  that 
it  would  require  many  hours  before  a  room  of,  say,  1000 
cubic  feet  capacity  would  lose  sufficient  oxygen  or  gain 
sufficient  carbon  dioxide  to  produce  the  slightest  apparent 
harmful  results,  even  though  ingress  of  fresh  air  were 
prevented;  and  yet  experience  tells  us  that  the  atmos- 
phere of  such  a  room  will  become  exceedingly  foul  and 
actually  detrimental  to  health  long  before  the  lapse 
of  time  necessary  to  exhale  sufficient  carbon  dioxide  to 
induce  serious  effects.  Moreover,  carbon  dioxide  is  odor- 
less, while  the  air  of  inhabited,  unventilated  rooms  is 
characterized  by  a  decidedly  offensive  smell  that  remains 
for  some  time  even  after  adequate  ventilation  has  been 
secured  and  when  chemical  tests  show  the  percentage 
of  carbon  dioxide  to  have  been  reduced  to  nearly  the 

1  Stevenson  and  Murphy,  vol.  i,  p,  945. 

2  American  Journal  of  Pharmacy,  1893,  p.  561. 

3  American  Text-book  of  Physiology,  p.  536. 
^  Text-book  of  Physiology,  4th  ed.,  p.  392. 


CARBON  DIOXIDE  IN  DWELLINGS  79 

normal.  "The  chemical  analyses  of  the  air  of  over- 
crowded rooms,  and  the  experiments  upon  animals  made 
by  many  investigators,  indicate  that  the  evil  effects  ob- 
served are  probably  not  due  to  the  comparatively  small 
proportions  of  carbonic  acid  usually  found  under  such  cir- 
cumstances. .  .  .  The  proportion  of  increase  of  CO2  and 
of  diminution  of  oxygen  which  has  been  found  to  exist  in 
badly  ventilated  churches,  schools,  theatres,  etc.,  is  not 
sufficiently  great  to  account  satisfactorily  for  the  great  dis- 
comfort which  such  conditions  produce  in  many  persons, 
and  there  is  no  evidence  that  such  an  amount  of  change 
in  the  normal  proportion  of  these  gases  has  any  influence 
upon  the  increase  of  disease  and  death-rates  which  statisti- 
cal evidence  has  shown  to  exist  among  persons  living  in 
crowded  and  un ventilated  rooms. "^  Therefore  it  must 
be  something  other  than  carbon  dioxide  that  vitiates 
the  air  of  dwellings  and  necessitates  the  provision  of  some 
system  of  ventilation.  However,  with  our  present  knowl- 
edge we  cannot  say  that  a  diminution  of  oxygen  and  an 
increase  of  carbon  dioxide  in  the  atmosphere  which  one 
breathes  habitually  do  not  tend  to  lower  the  general  tone 
and  perhaps  the  bactericidal  powers  of  the  body  and  thus 
to  render  it  more  susceptible  to  deleterious  influences, 
and,  since  there  is  some  evidence  that  as  the  carbon 
dioxide  in  the  atmosphere  increases  there  is  a  lessening  of 
the  amount  of  this  gas  excreted  from  the  body,  it  will 
on  general  principles  always  be  wiser  to  use  every  reason- 
able means  to  maintain  the  normal  proportion  of  the 
various  gases  in  the  atmosphere.  Moreover,  the  fact  that 
tuberculous  patients  usually  improve  if  they  live  contin- 
uously out  of  doors  would  seem  to  indicate  that  the  full 
quota  of  oxygen  in  the  air  is  essential  to  the  best  interests 
of  health,  and  also  that  in-door  air,  though  apparently 
but  slightly  impure,  favors  the  development  and  progress 
of  this  disease. 

1  The  Composition  of  Expired  Air  and  Its  Effect  upon  Animal  Life 
Mitchell,  Billings,  and  Bergey,  No.  989,  vol.  xxix,  Smithaonian  Con- 
tributions to  Knowledge. 


80  THE  ATMOSPHERE— AIR 

Aqueous  vapor  is  another  of  the  substances  excreted 
continually  from  both  the  lungs  and  the  skin;  but  it  is 
obvious  that  in  itself  it  cannot  be  directly  harmful  to  the 
system,  for  we  find  it  ever  present  in  all  natural  atmos- 
pheres, and  are  continually  replacing  by  imbibition  its  loss 
from  our  bodies.  The  quantity  daily  thrown  off  from 
the  lungs  and  skin  will  depend  on  the  temperature  and 
humidity  of  the  atmosphere,  the  quantity  of  air  inspired 
and  water  imbibed,  and  many  other  factors;  but  under 
ordinary  conditions  the  average  excretion  will  be  from 
100  to  1700  grammes  (about  3.5  to  60  fluidounces),  though 
increased  exertion  might  cause  even  the  latter  amount  tx) 
be  greatly  exceeded.  It  is  accordingly  possible  that  this 
large  quantity  of  moisture,  tending  to  saturate  an  atmos- 
phere already  humid,  and  thus  preventing  evaporation  from 
the  skin,  might  indirectly  and  reflexly  check  the  loss  of 
heat  from  the  body  and  the  excretion  of  waste  matters  by 
the  sweat-glands  and  that  the  retention  of  excessive  heat 
and  of  such  wastes  in  the  system  may  help  to  produce 
the  depression,  headache,  and  other  symptoms  experi- 
enced by  those  in  foul  and  humid  air.  It  has  been  noticed 
that  the  symptoms  due  to  foul  air  are  more  readily  mani- 
fested when  the  temperature  of  the  atmosphere  is  much 
below  or  much  above  the  usual  room-temperature  of  65° 
to  70°  F.  At  low  temperatures  the  air  is  readily  saturated, 
and  beside,  the  excreting  action  of  the  skin  is  much 
lessened  by  the  cold;  at  high  temperatures  the  humidity 
is  often  already  near  the  saturation-point,  while  the 
external  heat  tends  to  increase  the  quantity  of  water 
given  off  by  the  lungs  and  skin.  "At  high  tempera- 
tures the  respiratory  centers  are  affected  where  evapora- 
tion from  the  skin  and  mucous  surfaces  is  checked  by 
the  air  being  saturated  with  moisture — at  low  tempera- 
tures the  consumption  of  oxygen  increases  and  the  demand 
for  it^becomes  more  urgent."^  At  70°  F.  the  aqueous  ex- 
halation from  an  adult  body  would  in  an  hour  or  less  com- 

^  Mitchell,  Billings,  and  Bergey,  loc.  cit. 


HUMIDITY— CROWD-POISON  81 

pletely  saturate  from  350  to  600  cubic  feet  of  air  wh  ich  already 
has  the  not  unusual  relative  humidity  of  75  per  cent.,  while 
at  80°  F.  an  equal  or  even  greater  volume  of  air  would 
doubtless  gain  its  maximum  of  moisture  from  the  increase 
of  perspiration  due  to  the  extra  heat.  Moreover,  as  evapo- 
ration of  the  perspiration  is  one  of  the  most  important 
means  for  maintaining  the  balance  between  heat-produc- 
tion and  heat-dissipation,  interference  with  this  process 
naturally  tends  to  raise  the  body-temperature  rapidly  and 
to  produce  the  consequent  effects  upon  the  nervous 
mechanism.  A  stagnant  atmosphere,  therefore,  is  more 
depressing  than  one  in  motion,  even  though  temperature 
and  humidity  be  unaltered,  since  the  movement  of  the 
air  favors  evaporation  and  likewise  probably  acts  as  a 
gentle  stimulant  to  the  skin. 

Crowd-poison. — The  third  contaminant  given  to  air 
from  human  bodies  is  an  indefinite  volume  of  offensive 
organic  matter,  and  for  a  time  this  was  looked  upon  as  by 
far  the  most  harmful  part  of  animal  exhalations.  But 
recently  experiments  by  various  investigators  have  seemed 
to  indicate  that  this  organic  effluvium  is  not  so  dangerous 
as  it  has  hitherto  been  considered,  and  that  some,  at 
least,  of  the  symptoms  due  to  air  vitiated  by  respira- 
tion are  to  be  attributed  to  the  conditions  already  men- 
tioned, viz.,  increase  of  heat  and  moisture,  together  with 
lack  of  sufficient  air  movement.  It  is  also  doubtful 
whether  much,  if  any,  of  this  organic  matter  comes  from 
the  lungs  of  healthy  persons.^  '*  In  ordinary  quiet  respira- 
tion no  bacteria,  epithelial  scales,  or  particles  of  dead 
tissue  are  contained  in  the  expired  air.  .  .  .  The  cause  of 
unpleasant,  musty  odors  in  rooms  may  in  part  be  due  to 
volatile  products  of  decomposition  from  decayed  teeth, 
foul  mouths,  or  disorders  of  the  digestive  apparatus,  and 

*  Fliigge,  Hill,  and  others  have  found  that  the  evil  of  close  atmospheres 
is  largely  a  result  of  elevated  temperature,  humidity,  and  absence  of 
air  currents.  Tests  were  made  on  men  who  sat  in  impure  air,  but 
breathed  pure  air  through  tubes,  and  they  presented  all  the  symptoms 
usually  resulting  from  bad  ventilation.  Report  on  Human  ViUlity, 
Fisher,  p.  85. 
6 


82  THE  ATMOSPHERE— AIR 

in  part  to  volatile  iatty  acids  given  off  with  or  produced 
from  the  excretions  of  the  skin,  and  from  clothing  soiled 
with  such  excretions."^  However,  whatever  may  be  the 
exact  source  of  this  contamination,  we  know  this  concern- 
ing it — that  it  is  decidedly  offensive  to  the  sense  of  smell, 
that  it  is  organic  and  nitrogenous,  yielding  ammonia, 
darkening  sulphuric  acid,  decolorizing  potassium  perman- 
ganate, and  rendering  obnoxious  pure  water  through 
which  the  vitiated  air  has  been  drawn.  While  it  seemed 
to  such  careful  observers  as  Brown-Sequard,  d'Arsonval, 
Merkel,  and  others  to  be  directly  poisonous  to  lower 
animals,  modern  scientific  evidence  of  this  effect  is  lack 
ing.  In  general,  it  is  given  off  proportionately  with  the 
carbon  dioxide  from  the  body,  though  this  rule  is  not 
infallible;  it  is  apt  to  be  unevenly  distributed  through- 
out the  atmosphere  of  the  apartment,  and  is  probably 
therefore  not  truly  gaseous,  but  more  like  an  impalpable 
dust;  it  oxidizes  but  slowly,  being  evident  for  some  time 
after  fresh  air  has  been  admitted  and  the  carbon  dioxide 
has  been  reduced  almost  to  the  normal,  and,  while  neither 
condensed  nor  dissolved  in  the  aqueous  vapor  from  the 
body,  it  is  especially  attracted  and  retained  by  hygroscopic 
substances  such  as  wool,  paper,  feathers,  etc.  Its  smell 
is  generally  perceptible  when  the  respiratory  carbon  dioxide 
reaches  0.03  or  0.04  per  cent.,  sometimes  before  this  point 
is  reached,  especially  in  sick-rooms  or  hospital  wards,  and 
is  decidedly  offensive  when  the  total  carbon  dioxide 
approaches  0.1  per  cent. 

The  most  important  of  the  impurities  resulting  from 
the  combustion  of  coal,  the  principal  fuel  substance  used 
in  towns  and  cities,  are  soot  and  tarry  matters  (to  the  ex- 
tent of  about  1  per  cent,  of  the  coal  consumed),  carbon 
monoxide  and  dioxide,  aqueous  vapor,  and  more  or  less 
ammonium  sulphide,  carbon  disulphide,  hydrogen  sul- 
phide, sulphur,  sulphur  dioxide,  and  sulphuric  acid.  The 
relative  amounts  of  the  oxides  of  carbon — as  well   as 

1  Mitchell,  Billings,  and  Bergey,  loc,  cit. 


COMBUSTION-PRODUCTS  83 

of  the  oth^r  gases — will  depend  upon  the  perfection  of 
combustion;  "but  it  has  been  calculated  that  for  every 
ton  of  coal  burnt  in  London  something  like  three  tons  of 
carbon  dioxide  are  produced,"  and  as  the  coal  consump- 
tion of  that  city  is  over  30,000  tons  per  diem,  we  can 
readily  see  that  its  atmosphere  must  receive  the  enor- 
mous daily  contamination  of  about  300  tons  of  soot  and 
90,000  tons  of  carbonic  acid.  No  wonder  they  have  an 
occasional  fog  there! 

The  combustion-products  of  wood  are  in  the  main 
carbon  monoxide  and  dioxide  and  water,  while  those 
of  coke  and  of  gas  are  practically  the  same  as  those  of 
coal.  From  the  heating  apparatus,  if  properly  con- 
structed and  arranged,  these  products  pass  almost  directly 
to  the  exterior  of  dwellings  and  are  rapidly  dissipated 
in  spite  of  their  excessive  volume,  for  "diffusion  and  the 
ever-moving  air  rapidly  purify  the  atmosphere  from  carbon 
dioxide,"  and  in  fact  from  the  other  combustion-products 
also,  with  the  exception  of  the  soot  and  tarry  products. 

Should,  however,  combustion  be  incomplete,  or  should 
the  stoves  or  other  heating  apparatus  be  imperfect,  the 
gases  may  seriously  or  even  dangerously  contaminate  the 
house-air,  the  deadly  carbon  monoxide  being  particularly 
liable  to  leak  not  only  through  the  crevices,  but  actually 
through  the  heated  cast-iron  plates,  etc.,  of  stoves  and 
furnaces.  Theoretically,  a  pound  of  coal  requires  160 
cubic  feet  of  air  for  its  perfect  combustion,  but  actually 
from  one-half  to  as  much  more  must  be  supplied  to  the 
ordinary  heating  apparatus  to  secure  complete  oxidation 
of  the  fuel. 

Practically  all  the  devices  for  artificial  illumination, 
with  the  exception  of  the  incandescent  electric  light,  give 
off  directly  to  the  surrounding  air  combustion-products 
which  are  much  the  same  as  those  from  coal,  and  this 
contamination  is  consequently  a  positive  factor  in  the 
vitiation  of  in-door  air.  "Every  cubic  foot  of  coal-gas 
yields,  on  combustion,  roughly,  half  its  own  volume,  or 
0.52  cubic  foot,  of  carbon  dioxide,  and  1.34  cubic  foot  of 


84  THE  ATMOSPHERE— AIR 

water  vapor,"  besides  some  little  carbon  moi^oxide  when 
ordinary  burners  are  used.  "Speaking  generally,  it  may 
be  said  that  each  cubic  foot  of  gas  burnt  per  hour  from 
the  ordinary  burners  vitiates  as  much  air  as  would  be 
rendered  impure  by  the  respiration  of  an  individual; 
it  at  the  same  time  will  raise  the  temperature  of  31,290 
cubic  feet  of  air  1  degree  F.,  and  yields  217  calories  (a 
kilogramme  of  water  heated  1  degree  C.)  or  860  British 
heat-units  (a  pound  of  water  heated  1  degree  F.)."^  But 
inasmuch  as  the  products  of  combustion  are  superheated, 
they  rise  at  once  to  the  top  of  the  room  and  usually,  for 
the  most  part,  quickly  escape  to  the  outer  air  through  the 
combined  influence  of  negative  gravity  and  diffusion;  so 
that  comparatively  little  air  is  needed  to  dilute  the  small 
proportion  of  such  products  that  eventually  cool  and  fall 
to  the  breathing-level. 

The  accompanying  table^  shows  the  influence  of  various 
lighting  agents  with  respect  to  the  condition  of  the 
room-air. 

From  this  table  it  will  be  learned  that  the  incandes- 
cent electric  light  is  the  most  satisfactory  from  a  hygienic 
point  of  view,  and  there  is  no  doubt  that  its  very  general 
introduction  has  done  much  toward  obviating  a  constant 
source  of  vitiation,  especially  in  rooms  which  require 
much  artificial  light,  and  are  at  the  same  time  diffi- 
cult to  ventilate.  It  is  said  that  in  a  bank  in  London, 
in  which  several  hundred  persons  are  employed,  the 
absences  on  account  of  illness  have  been  so  far  reduced, 
apparently  by  the  introduction  of  the  incandescent  electric 
light  alone,  that  the  extra  labor  gained  has  more  than 
compensated  for  the  increased  cost  of  lighting.  The  general 
use  of  tungsten  instead  of  carbon  filaments  for  incandes- 
cent electric  lamps  is  a  recent  improvement  that  provides 
a  whiter,  steadier  and  more  brilliant  light,  and  at  a 
reduced  cost  for  current.  The  electric  arc  light  is  said 
to  form  nitric  acid;  but  even  so,  its  effects  are  not  so 

1  Notter  and  Firth,  Treatise  on  Hygiene,  p.  140. 
« Ibid.,  p.  141. 


APPARATUS  FOR  LIGHTING 


85 


harmful  as  are  those  of  the  products  of  combustion  of 
the  ordinary  candle,  lamp,  or  gas-jet. 


Quantity 
consumed. 

i 
1 

1 

il 

it 

It 

?3 

II 
:|5 

Tallow  candles    .      .      . 

2200  grains 

16 

Cu.  ft. 
10.7 

Cu.  ft. 
7.3 

Cu.  ft. 
8.2 

1400 

12. 0 

Sperm  candles 

1740      " 

16 

9.6 

6.5 

6.5 

1137 

11.0 

Paraffin-oil  lamp 

992       " 

16 

6.2 

4.5 

3.5 

1030 

7.5 

Kerosene-oil  lamp 

909       " 

16 

5.9 

4.1 

3.3 

1030 

7.0 

Coal-gas  No.  5  batwing 
burner 

5.5  cu.  ft. 

16 

6.5 

2.8 

7.3 

1194 

5.0 

Coal-gas,  Argand  burner 

4.8       " 

16 

5.8 

2.6 

6.4 

1240 

4  3 

Coal-gas,      regeneration 
(Siemens)  burner) 

3.2      " 

32 

3.6 

1.7 

4.2 

760 

2.8 

Coal-gas    (Welsbach  in- 
candescent)     .      .      . 

3.5      " 

50 

4.1 

1.8 

4.7 

763 

3.0 

Electric        incandescent 
light 

0.3  1b.  coal 

16 

0.0 

0.0 

0.0 

37 

0,0 

Next  to  the  incandescent  electric  lijjht  in  importance 
are  the  Welsbach  and  Siemens  gas-lights;  but  of  these  the 
latter  has  not  the  illuminating  power,  nor  is  it  so  well 
adapted  to  house  use  as  is  the  former.  The  Welsbach 
light  makes  use  of  the  Bunsen  flame  (in  which,  by  the 
way,  the  carbon  of  the  gaseous  fuel  is  completely  oxi- 
dized and  converted  into  carbon  dioxide)  to  render 
incandescent  a  non-combustible  mantle  or  network,  com- 
posed of  vegetable  fiber  saturated  with  the  oxides  of 
certain  metals  which  have  the  property  of  becoming 
intensely  luminous  when  sufficiently  heated.  It  gives  a 
white  light  of  great  illuminating  and  considerable  actinic 
power,  and  of  practically  unvarying  intensity.  In  fact, 
this  quality  of  steadiness,  in  which  it  even  surpasses  the 
earlier  types  of  incandescent  electric  light,  is  by  no  means 


86 


THE  ATMOSPHERE— AIR 


the  least  of  its  hygienic  advantages,  since  such  steadiness 
is  an  important  factor  in  the  conservation  of  the  eyesight. 
Recently  hydrocarbon  (kerosene  and  gasoline)  lamps, 
making  use  of  an  incandescent  mantle  similar  to  the 
Welsbach,  have  been  placed  on  the  market,  and  are  said 
to  be  safe  and  free  from  odor  or  danger  of  explosion.    If 


Chimney. 


fra — Shade  Support. 


Mantle. 
^^  Mantle  Support. 

Chimney  Support. 
Gauze  Tip. 

Gas  Spreader. 
Corrugated  Cap. 

antle  Carrier. 
Centre  Tube. 

Bobesche  Support. 
Gallery. 
Bunsen  Tube. 


Air  Shutter. 

Adjustable  Check. 
Fig.  14.— Welsbach  light. 

these  claims  can  be  sustained,  such  lamps  are  of  value, 
since  they  furnish  a  powerful  and  steady  incandescent 
light  at  very  low  cost. 

A  comparatively  new  illuminant,  not  mentioned  in  the 
foregoing  table,  is  acetylene  gas.  This  gives  a  very  white 
and  powerfully  actinic  light,  and,  on  account  of  ease  of 


SEWER-GAS  AND  SOIL-AIR  87 

production  and  the  small  amount  needed  for  ordinary 
lighting,  is  cheap  and  does  not  greatly  vitiate  the  atmos- 
phere. But  a  mixture  of  the  unburned  acetylene  with  air 
in  proportions  of  from  4  to  25  per  cent,  is  highly  explosive, 
and  consequently  the  gas  is  not  yet  much  used  for  interior 
lighting. 

SEWER-GAS   AND   SOIL-AIR. 

What  is  commonly  called  sewer-gas  is  a  mixture  of  a 
number  of  gases,  such  as  carbon  dioxide,  carburetted 
hydrogen,  ammonium  and  hydrogen  sulphide,  nitrogen, 
etc.,  together  with  a  considerable  amount  of  fetid  organic 
matters,  the  volatile  or  semivolatile  products  of  animal 
and  vegetable  decomposition,  all  varying  according  to 
the  condition  of  the  sewer,  the  kind  of  matter  received 
therein,  the  amount  of  surface-water,  etc.  The  air  from 
a  closed  cesspool  may  be  extremely  foul  and  poisonous, 
so  much  so  that  the  emanations  have  not  infrequently 
caused  death  in  those  who  inhaled  them  in  full  concen- 
tration; on  the  other  hand,  the  atmosphere  of  a  properly 
constructed  and  well-flushed  sewer  may  be  almost  as  pure 
as  that  above  the  surface  of  the  ground.  Bacteria  are 
present  in  varying  numbers,  with  the  possibility  of  some 
of  them  being  the  germs  of  specific  diseases.  But  fresh 
sewage  is  not  so  likely  to  contaminate  the  air  above  it 
with  microbes  as  that  in  which  decomposition  has  begun, 
since  Frankland  has  shown  that  solid  or  liquid  particles 
are  not  liable  to  be  scattered  into  the  air  by  any  disturb- 
ance to  which  the  sewage  may  be  subjected  until  gases  of 
decomposition  are  produced.  According  to  some  writers, 
the  bursting  of  bubbles  of  gas  on  the  surface  may  dis- 
charge the  bacteria  into  the  sewer-air.  It  has  also  been 
shown  that  "  bacteria  can  undoubtedly  grow  up  the  sides 
or  walls  of  damp,  nutrient  sewers,  and  if  these  latter 
become  at  all  dry,  air  currents  readily  detach  and  dis- 
perse them."  It  is,  however,  questionable  whether  many 
disease  germs  can  withstand  the  natural  antagonism  of 


88  THE  ATMOSPHERE— AIR 

the   saprophytic   bacteria   that   predominate   in   sewage 
and  on  sewer  walls. 

Another  class  of  impurities  that  may  at  times  be  found 
in  the  air  of  dwellings  comprises  those  coming  from  the 
soil  and  soil-air.     The  soil,  in  hygiene,  refers  to  all  that 


..^•'i;, 


-0 


,  <;> 


Fig.  15. — Apparatus  for  determination  of  carbon  dioxide  in  soil-air. 
(Harrington.) 


portion  of  the  earth's  crust  that  can  in  any  way  affect  the 
health.  All  soils  contain  more  or  less  air — soft  sandstones 
from  20  to  40  per  cent.,  loose  sand  from  40  to  50  per 
cent.,  and  loose  soils  often  very  much  more. 

As  the  soil  is  the  recipient  of  most  of  the  solid  and 


COMPOSITION  OF  SOIL-AIR  89 

liquid  waste  of  all  animal-  and  vegetable-life,  and  as  the 
myriads  of  saprophytic  bacteria  that  inhabit  its  upper 
strata  are  constantly  working  to  convert  this  dead  organic 
matter  into  simpler  compounds  suited  to  the  nourishment 
of  plant-life,  the  soil-air,  taking  the  atmosphere  above  as 
a  standard,  will  usually  be  far  from  pure.^  It  is  rich  in 
carbon  dioxide  and  in  organic  vapors  and  gases,  while  the 
proportion  of  oxygen  is  probably  always  less  than  that  of 
the  air  above  ground.  Moreover,  the  carbon  dioxide 
increases  and  the  oxygen  decreases  the  deeper  below  the 
surface  the  sample  is  taken.  As  much  of  the  carbon 
dioxide  is  evidently  derived  from  organic  pollutions,  it 
might  be  supposed  that  this  gas  could  be  taken  as  an  index 
of  the  degree  of  the  latter,  and  so  it  might  if  other  condi- 
tions, such  as  permeability  of  soil,  rate  of  circulation,  etc., 
were  always  the  same.  But  they  are  not,  and  the  composi- 
tion of  the  soil-air  is  practically  not  the  same  at  any  two 
places,  nor  for  the  same  place  at  different  times.  The 
underground-air  is  constantly  in  circulation,  even  to  a 
considerable  depth;  but  there  is  a  hindrance  to  its  free 
movement  and  diffusibility,  and  this,  together  with  the 
great  variation  in  the  distribution  of  oxidizable  and  other 
contaminating  matters,  causes  the  variations  in  its  com- 
position. The  carbon  dioxide  therefore  cannot  be  taken 
as  an  index  of  the  relative  purity. 

The  forces  that  maintain  the  circulation  of  the  ground- 
air  are  the  wind,  the  daily  change  of  surface  temperature, 
the  fall  of  rain,  and  especially  in  winter  the  local  and  arti- 
ficial conditions  of  civilization.  A  very  slight  wind  will 
drive  air  through  the  soil  for  long  distances,  the  rise  and 
fall  of  the  ground-water  has  its  obvious  effect,  and  the 
movement  due  even  to  slight  changes  of  temperature  is 
likely  to  be  quite  extensive  and  positive. 

Owing  to  evaporation  from  the  ground-water,  the  soil- 

>  Too  much  importance  cannot  be  attributed  to  this  saprophytic  action 
in  the  upper  soil,  for  it  is  one  of  nature's  wonderful  methods  of  securing 
and  conserving  not  only  the  purity  of  our  environment,  but  also  the 
perpetuation  of  organic  life. 


90  THE  ATMOSPHERE— AIR 

air  is  always  quite  humid,  and,  according  to  some  writers, 
may  also  be  laden  with  bacteria  and  other  very  light  sub- 
stances lifted  up  by  the  ascensional  power  of  evaporation. 

As  sewage,  house-wastes,  and  dirt  of  all  kinds  are  par- 
ticularly liable  to  contaminate  the  soil  about  any  inhabited 
dwelling,  the  air  of  that  soil  will  more  than  likely  be 
very  impure,  and  care  must  be  taken  that  it  is  not  drawn 
into  the  house.  This  is  especially  apt  to  happen  in  cold 
weather,  when  house-fires  are  lighted  and  the  in-door  air 
is  thus  made  warmer  than  that  without,  the  tendency  then 
being  for  the  soil-air  to  pass,  if  possible,  through  the  cellar 
walls  and  floors.  These  should  be  made  as  nearly  air-tight 
as  possible,  and  special  attention  should  be  given  to  the 
space  underneath  and  about  the  furnaces  or  basement 
heating  apparatus.  As  an  instance  of  the  importance  of 
these  precautions,  Hime^  gives  an  account  of  the  death 
of  four  persons.  Enough  illuminating-  (coal-)  gas  was 
drawn  from  a  broken  pipe  fifteen  feet  distant  from  the 
foundation  walls  of  the  dwelling  to  cause  the  fatality, 
although  there  were  only  eight  or  ten  inches  of  tramped 
earth  above  the  pipe  and  the  only  aspirating  force  was  the 
difference  of  temperature  within  and  without  the  house. 
A  number  of  explosions  have  occurred,  due  to  a  similar 
leakage  of  gas  from  street  mains  through  basement  walls 
or  into  drains  and  sewers,  since  the  admixture  of  illumi- 
nating-gas with  air  forms  a  most  powerful  and  dangerous 
explosive. 

There  is  no  direct  evidence  that  the  emanations  from 
piggeries,  bone-yards,  soap-factories,  garbage-incinerators, 
etc.,  are  actually  harmful  to  health;  but  they  may  be 
very  decided  nuisances  to  those  living  near  by,  and  may 
also  foster  the  excessive  multiplication  of  flies,  rats,  etc., 
therefore,  all  such  places  should  be  strictly  controlled  by 
the  proper  sanitary  authorities. 

The  atmosphere  of  mines  and  other  excavations  is  sub- 
ject to  contamination  by  the  excess  of  carbon  dioxide  in 

1  Stevenson  and  Murphy,  Treatise  on  Hygiene,  vol.  i,  p.  949. 


DISEASES  CAUSED  BY  IMPURE  AIR  91 

the  soil-air,  by  gases  from  blasting  agents  and  from  fis- 
sures in  rock,  and  by  the  products  of  respiration  from 
men  and  animals  working  in  the  mines,  etc.  The  air  in 
deep  cellars  or  basements,  or  in  the  holds  of  ships  is  also 
likely  to  be  foul,  owing  to  the  difficulty  of  changing  it 
sufficiently  often,  and  frequently  also  to  the  insanitary 
character  of  stored  contents  or  cargoes.  In  such  situa- 
tions proper  ventilation  should  be  secured  by  all  means 
available,  and  special  care  taken  that  the  impure  air  does 
not  affect  the  laborers  in  the  one  case  or  the  passengers 
and  crew  in  the  other. 


DISEASES   CAUSED   BY   IMPURE    AIR. 

As  a  rule,  the  human  system  has  the  power  of  accom- 
modating itself,  through  habit,  to  withstand  influences 
which,  in  one  unaccustomed  to  them,  would  soon  produce 
serious  results.  But  in  spite  of  this,  if  the  body  be  ex- 
posed for  any  considerable  length  of  time  to  conditions 
of  impurity  or  deterioration  in  its  supply  of  air,  water,  or 
food,  such  conditions  will  always  tend  to  undermine 
health  and  increase  the  susceptibility  to  disease,  even 
though  they  cause  no  more  serious  results.  "Statistical 
inquiries  on  mortality  prove  beyond  a  doubt  that  of  the 
causes  of  death  which  are  usually  in  action,  impurity 
of.  the  air  is  most  important.  No  one  who  has  paid  any 
attention  to  the  condition  of  health  and  the  recovery  from 
disease  of  those  persons  who  fall  under  his  observation, 
can  doubt  that  impurity  of  the  air  marvellously  afl'ects 
the  first,  and  influences  and  sometimes  even  regulates 
the  second.  .  .  .  The  air  may  affect  health  by 
variations  in  the  amount  or  conditions  of  its  normal 
constituents,  by  differences  in  physical  properties,  or  by 
the  presence  of  impurities.  While  the  immense  effect 
of  impure  air  cannot  be  for  a  moment  doubted,  it  is  not 
always  easy  to  assign  to  each  impurity  its  definite  action. 
The  evidences  of  injury  to  health  from  impure  air  are 
found  in  a  larger  proportion  of  ill  health — i.  <*.,  of  days 


92  THE  ATMOSPHERE— AIR 

lost  from  sickness  in  the  year — than  under  other  circum- 
stances; an  increase  in  the  severity  of  many  diseases, 
which,  though  not  caused,  are  influenced  by  impure  air, 
and  a  higher  rate  of  mortality,  especially  among  children, 
whose  delicate  frames  always  give  us  the  best  test  of  food 
and  air."i  These  facts  are  now  so  well  recognized  that 
an  abundant  supply  of  fresh,  clean  air  is  regarded  as  essen- 
tial in  the  treatment  of  many  diseases,  and  the  practise  of 
living  as  much  as  possible  and  even  sleeping  out-of-doors 
is  widely  advocated. 

The  definite  diseases  caused  by  the  solid  impurities 
in  the  atmosphere  are  almost  all  such  as  affect  the  res- 
piratory passages  and  organs,  with  the  possible  excep- 
tion of  those  engendered  by  specific  bacteria  and  other 
microbes.  Much  therefore  depends  upon  the  physical 
character  of  the  solid  impurities.  Soft  particles  and  those 
with  edges  smooth  and  rounded,  like  soot  and  coal-dust, 
may  apparently  do  nothing  more  than  coat  or  clog  the 
air-vesicles  and  finer  bronchial  tubes,  and  in  this  way 
diminish  the  area  of  lung  tissue  exposed  to  the  inspired  air, 
although  it  is  questionable  whether  any  foreign  matter  in 
the  lungs  does  not  cause  more  or  less  irritation.  With 
most  of  us,  however,  such  impurities  are  of  little  account  if 
care  be  taken  to  develop  the  full  respiratory  capacity  of  the 
chest;  but  where  the  air  is  heavily  charged  with  such  dust 
it  has  a  positive  effect  upon  health  and  duration  of  life. 
In  1862  Sir  John  Simon  stated  that  with  one  exception 
"the  300,000  (coal)  miners  of  England  and  Wales  break 
down  as  a  class  prematurely  from  bronchitis  and  pneu- 
monia, caused  by  the  atmosphere  in  which  they  live.  The 
exception  is  important.  The  colliers  of  Durham  and 
Northumberland,  where  the  mines  are  well  ventilated,  do 
not  appear  to  suffer  from  an  excess  of  pulmonary  diseases, 
or  do  so  in  a  slight  degree  only."  Happily,  since  this  was 
written  satisfactory  ventilation  systems  have  been  placed 
in  most  of  the  collieries  of  England,  and  the  condition  of 

1  Stevenson  and  Murphy,  vol.  i ,  pp.  121  and  122. 


EFFECT  OF  DUST  IN  AIR  93 

the  laborers  correspondingly  improved;  but  coal-miners 
are  still,  as  a  class,  particularly  liable  to  bronchitis,  pneu- 
monia, asthma,  emphysema,  and  fibrosis  (fibroid  phthisis), 
though  they  seem  to  be  but  slightly  subject  to  primary 
tuberculosis  of  the  lungs  or  other  organs. 

On  the  other  hand,  if  the  particles  of  dust  in  the  air 
are  hard,  angular,  and  sharp,  the  lung  tissues  are  readily 
lacerated,  inflammatory  processes  are  quickly  set  up,  and 
the  opportunity  for  the  inoculation  of  tubercle  bacilli  and 
other  disease  germs  is  very  great.  The  mortality  from 
tubercular  phthisis  among  metal-miners,  needle-cutters, 
steel-grinders  and  tool-grinders,  etc.,  is  remarkable, 
and  they  are  also  especially  subject  to  asthma  and 
emphysema.  Among  Cornish  tin-miners,  68  per  cent, 
of  all  sick  are  consumptive;  of  needle-makers,  over  60 
per  cent. ;  of  flint-cutters,  glass-cutters  and  -polishers,  and 
of  grindstone-makers,  from  80  to  90  per  cent.,  etc.  It  is 
said  that  a  mixture  of  mineral  and  metallic  dust  seems  to 
be  more  harmful  than  metallic  dust  alone,  perhaps  because  of 
the  greater  clogging  of  the  air- vesicles  by  the  mineral  matter. 

Likewise,  with  other  occupations  where  there  is  much 
irritative  dust  floating  in  the  air,  the  effect  upon  the 
health  of  the  worker  is  marked,  and  we  find  lung  troubles 
prevalent  and  many  suffering  and  dying  from  phthisis, 
as,  for  instance,  among  cotton-spinners,  flax-dressers, 
hemp-dressers,  pottery-makers,  etc.  Defective  ventila- 
tion, accumulations  of  noxious  gases,  improper  habits, 
insufficient  disinfection  of  sputa,  and  often  the  excessive 
humidity  of  the  air  necessary'  in  some  of  these  pursuits, 
have  doubtless  something  to  do  with  the  high  sick-rates 
and  death-rates;  but  withal,  the  marked  effect  of  the  solid 
atmospheric  impurities  cannot  be  denied. 

Again,  workers  in  poisonous  metals,  compounds,  or 
gases,  such  as  paint-makers  and  painters,  type-setters, 
gilders  (using  mercury),  brass-founders,  coppersmiths, 
etc.,  are  subject  to  the  influence  of  the  respective  poisons 
and  the  symptoms  produced  by  them,  with  a  correspond- 
ingly increased  mortality. 


94  THE  ATMOSPHERE— AIR 

Among  the  diseases  that  may  be  caused  by  the  inhalation 
or  swallowing  of  specific  microorganisms  floating  in  the 
atmosphere  are  erysipelas,  measles,  scarlet  fever,  diphtheria, 
whooping-cough,  infectious  pneumonia,  phthisis  and  other 
forms  of  tuberculosis,  and  epidemic  influenza ;  and  although 
the  germs  of  cholera  and  typhoid  fever  are  usually  car- 
ried by  the  drinking-water  or  food,  they  doubtless  do 
sometimes  find  their  way  into  the  system  from  a  con- 
taminated atmosphere.^ 

Only  recently  has  the  importance  of  "droplet  infec- 
tion "been  sufficiently  appreciated.'  By  this  term  is 
meant  the  transmission  of  disease  by  the  germ-carrying 
spray  or  moisture  discharged  from  the  mouths  and 
and  respiratory  apparatus  of  sick  persons  or  disease 
"carriers"  into  the  surrounding  atmosphere  by  cough- 
ing, sneezing,  cheering  or  forcible  speaking.  It  is  more 
than  probable  that  a  very  large,  if  not  the  greater,  part  of 
the  infection  of  the  disastrous  and  widespread  influenzal 
epidemic  in  the  autumn  of  1918  was  due  to  this  mode  of 
transmission. 

Lastly,  the  spores  of  certain  fungi  which  have  been 
found  in  the  air  of  hospitals  and  elsewhere  are  known  to 
cause  certain  skin  diseases,  such  as  tinea  and  favus; 
and  it  is  almost  as  certain  that  the  irritating  or  poisonous 
pollen  of  certain  grasses  and  other  plants  have  much  to 
do  with  the  causation  or  aggravation  of  such  maladies  as 
hay-fever  or  rose-cold. 

From  what  has  been  said,  it  will  be  surmised  that  it 
is  scarcely  possible  at  present  to  specify  the  exact  effect 
upon  the  health  of  each  of  the  impurities  and  influences 
communicated  to  the  air  by  the  human  body,  and  that 
the  symptoms  observed  to  be  due  to  air  thus  vitiated  are 
very  probably  an  evidence  and  result  of  the  combined 


1  The  report  of  the  commission  appointed  to  inquire  into  the  preva- 
lence and  causes  of  typhoid  fever  in  the  late  Spanish- American  War  shows 
that  in  some  cases  infection  was  probably  due  to  the  dust  in  the  atmos- 
phere which  had  been  raised  by  many  passing  feet  from  the  roads  over 
which  leaking  sewage  wagons  had  been  hauled. 


EFFECTS  OF  HUMAN  EXHALATIONS  95 

action  of  these  factors  rather  than  of  any  one  of  them 
singly.  However,  the  writer  feels  that  the  oppression  so 
commonly  experienced  in  an  unventilated  room  is  often 
fairly  attributable  to  the  increase  in  the  temperature  and 
humidity  and  to  air-stagnation  or  lack  of  sufficient 
movement;  that  the  headache,  disturbed  nutrition,  and 
febrile  condition,  lasting  for  hours  and  sometimes  days 
after  exposure  to  air  thus  vitiated,  are  probably  due  to 
the  same  factors  together  with  the  reflex  influence  of  the 
organic  matter  upon  the  system,  and  possibly  also,  in 
part,  to  the  suppression  of  cutaneous  excretion  dependent 
upon  the  high  content  of  moisture  in  the  air;  and  that 
the  respiratory  carbon  dioxide  by  itself  can  but  rarely 
have  much  influence  upon  comfort  or  health. 

If  the  respiratory  and  cutaneous  vitiation  be  sufficient 
to  produce  acute  effects,  the  immediate  symptoms  will  be 
discomfort  and  a  sense  of  oppression,  followed  by  head- 
ache and  not  rarely  nausea,  and  a  rather  decided  rise  of 
temperature,  all  of  which  may  last  for  some  time  even 
after  the  individual  goes  into  perfectly  pure  air.  Those 
who  habitually  live  in  such  an  atmosphere  are  almost  uni- 
formly languid,  pallid  and  anemic,  subject  to  headaches, 
nausea  and  loss  of  appetite,  and  often  to  skin  disorders, 
and  are  undoubtedly  markedly  predisposed  to  phthisis, 
pneumonia,  bronchitis,  scrofula,  rhachitis,  etc.  Moreover, 
such  an  atmosphere  apparently  favors  the  rapid  spread  of, 
increases  the  severity  of,  and  retards  the  convalescence 
from,  such  diseases  as  diphtheria,  scarlet  fever,  measles, 
typhus,  smallpox,  etc.  This  may  be  due  rather  to  the 
vitiated  atmosphere  causing  a  decrease  of  bodily  resis- 
tance and  an  increase  in  predisposition  to*  such  maladies, 
than  to  the  accumulation  or  the  actual  multiplication  by 
growth  of  the  disease  germs  in  the  foul  air. 

When  the  condition  of  the  air  is  very  bad,  the  results 
may  be  serious  and  even  fatal,  as  in  the  well-known  cases 
of  the  "Black  Hole  of  Calcutta";  of  the  prison  in  which 
300  captives  of  war  were  crowded  after  the  battle  of 
Austerlitz  (260  dying  very  soon  after  being  placed  therein) ; 


96  THE  ATMOSPHERE— AIR 

and  of  the  steamer  "Londonderry,"  in  which,  of  200 
steerage  passengers  who  were  temporarily  crowded  into 
a  cabin  (18x11x7  feet)  during  a  storm  of  only  a  few 
hours'  duration,  72  were  dead  and  others  dying  when 
the  cabin  was  opened:  but  in  these  instances  the  lack 
of  oxygen  may  have  also  been  a  very  important  factor 
in  the  results. 

As  regards  the  influence  of  combustion-products  on 
health,  it  will  suffice  to  detail  the  symptoms  resulting 
from  inhalation  of  the  various  gases.  It  will  be  difficult 
to  show  that  these  gases,  together  with  the  coincident  soot, 
have  any  general  effect  upon  health  when  escaping  into 
the  out-door  atmosphere,  even  when  produced  in  such 
enormous  quantities  in  cities  as  has  been  already  indicated. 
It  is  possible  that  the  sulphur  dioxide  and  other  sulphur 
gases  may  predispose  to,  or  aggravate  attacks  of,  bron- 
chitis or  asthma  in  those  living  in  the  vicinity  of  gas-works, 
chemical  factories,  etc.,  but  too  little  comes  from  the 
chimneys  of  dwelling-houses  to  do  much,  if  any,  harm. 

In-doors  the  case  is  different,  for  the  gases  from  lights 
and  fires  become  more  and  more  concentrated  if  the  ven- 
tilation be  insufficient.  The  possible  effects  of  varying 
percentages  of  carbon  dioxide  have  been  noted.  We  have 
no  evidence  of  cases  of  chronic  poisoning  by  this  gas, 
although,  as  Parkes  says:  "The  presence  of  a  very  large 
amount  of  CO2  in  the  air  may  lessen  its  elimination  from 
the  lungs,  and  thus  retain  the  gas  in  the  blood,  and  thus  in 
time  possibly  produce  serious  alterations  in  nutrition." 

In  cases  of  acute  poisoning  by  this  gas — i.  e.,  where  it 
is  in  great  excess  in  the  atmosphere — there  is  an  almost 
immediate  loss  of  muscular  power,  and  the  person  may 
consequently  be  unable  to  remove  himself  from  the  place 
of  danger,  while  others  who  go  to  help  him  may  also  suc- 
cumb and  more  than  one  be  asphyxiated.  Accordingly,^ 
volunteer  rescuers  should  always  remember  to  act  with 
coolness  and  great  rapidity,  and  to  provide  means  for  the 
prompt  removal  not  only  of  the  ones  they  would  save,  but 
of  themselves  as  well.     Fortunately,  when  one  who  has 


INFLUENCE  OF  COMBUSTION-PRODUCTS         97 

been  overcome  by  carbon  dioxide  is  brought  into  an  atmos- 
phere of  pure  air  before  life  is  extinct  and  is  aided  by 
artificial  respiration,  he  usually  recovers  quickly  and  com- 
pletely because  of  the  rapid  escape  of  the  excess  of  the 
gas  from  the  blood  and  its  replacement  by  the  necessary 
oxygen.  Death  from  carbon  dioxide  poisoning  is  prob- 
ably mainly  due  to  asphyxia,  partly  from  lack  of  oxygen 
and  partly  from  paralysis  of  the  respiratory  muscles, 
although  the  latter,  as  well  as  the  general  motor  palsy, 
would  seem  to  indicate  that  the  gas  itself  had  also  a  posi- 
tive physiological  and  toxic  effect  upon  the  nerve-centers. 

Cases  of  poisoning  by  carbon  monoxide  are  much  more 
serious.  Recovery  from  its  effects  is  slow  and  uncertain, 
because  this  gas  tenaciously  unites  with  the  hemoglobin 
of  the  red  blood-corpuscles,  paralyzing  them  as  it  were, 
and  rendering  them  unable  longer  to  act  as  oxygen- 
carriers  to  the  tissues;  while  the  union  of  carbon  dioxide 
with  the  blood  is  always  a  much  less  stable  one  and  is 
readily  dissolved  as  soon  as  interchange  with  a  normal 
atmosphere  is  available.  Less  than  0.5  per  cent,  of 
carbon  monoxide  in  the  air  has  caused  s\Tnptoms  of 
poisoning,  and  Roseman  states  that  "air  containing  0.4 
per  cent,  may,  in  one  hour,  prove  fatal."  It  appears 
that  the  gas,  volume  for  volume,  completely  rsplaces 
the  oxygen  in  the  blood,  and  cannot  again  be  displaced 
by  oxygen,  so  that  the  person  dies  asph^Tciated;  but 
Pokrowsky  has  shown  that  it  may  be  gradually  con- 
verted into  carbon  dioxide  and  be  got  rid  of,"  if  life  be 
maintained  sufficiently  long. 

The  symptoms  of  carbonous  oxide  (monoxide)  poisoning 
are  feebleness,  oppressed  breathing,  trembling,  and  ina- 
bility to  swallow;  then  "loss  of  consciousness,  destruction 
of  reflex  action,  and  finally  paralysis  of  the  heart."  "  Hirt 
says  that  at  high  temperatures  (25°  to.  32°  C.  =  77°  to 
90°  F.)  it  produces  convulsions,  but  not  at  low  tempera- 
tures (8°  to  12°  C.  =  46°  to  54°  F.)."  The  blood  and 
muscles  are  made  a  brilliant  red  by  this  gas;  darkened  by 
carbon  dioxide.  Claude  Bernard  says  that  a  mixture  of 
7 


98  THE  ATMOSPHERE— AIR 

these  gases  is  more  destructive  than  either  separately, 
probably  because  the  excess  of  the  acid-gas  interferes 
with  the  conversion  of  the  monoxide  and  its  elimination 
from  the  blood,  a  process  that  is  always  slow  and  uncer- 
tain under  the  best  of  conditions. 

Illuminating-  or  coal-gas — composed  of  hydrogen,  light 
and  heavy  carburetted  hydrogens,  a  little  nitrogen,  and 
carbon  dioxide,  and  from  5  to  7  per  cent.,  or  even  more, 
of  carbon  monoxide — rapidly  causes,  when  inhaled,  giddi- 
ness, headache,  nausea  and  vomiting  (occasionally),  confu- 
sion of  intellect,  loss  of  consciousness,  general  weakness 
and  depression,  partial  paralysis,  convulsions,  and  the 
usual  symptoms  of  asphyxia.  Mixed  in  large  proportions 
with  the  air,  death  may  ensue  comparatively  quickly, 
probably  because  of  the  large  content  of  carbon  monoxide. 
It  is  well  to  remember  that  the  so-called  water-gas,  now 
so  extensively  manufactured  for  fuel  purposes  and  also  for 
diluting  coal-gas,  contains  a  much  larger  percentage  of 
carbon  monoxide  (sometimes  from  30  to  40  per  cent.) 
than  coal-gas,  and  that  the  effects  resulting  from  inhala- 
tion of  a  mixture  of  the  two  will  in  all  likelihood  be  more 
marked,  more  rapid,  and  more  deadly  than  with  undi- 
luted coal-gas.  Much  harm  may  likewise  occur  when 
even  small  quantities  of  this  mixed  gas  are  breathed  from 
day  to  day,  and  there  can  scarcely  be  a  doubt  that  the 
cause  of  many  of  the  troublesome  anemias  might  be 
traced  to  unnoticed  or  uncared-for  leaks  in  the  gas-pipes 
of  dwellings. 

"The  effects  of  constantly  inhaling  the  products  of  gas 
combustion  may  be  seen  in  the  case  of  workmen  whose 
shops  are  dark  and  who  are  compelled  to  burn  gas  during 
a  large  part  of  the  day;  the  pallor,  or  even  anemia  and 
general  want  of  tone,  which  such  men  show,  are  owing 
to  the  constant  inhalation  of  an  atmosphere  so  impure." 

Sulphurous  acid-gas  (S2O)  and  hydrogen  sulphide  (H2S) 
are  each  fatal  to  life,  the  latter  when  in  a  compara- 
tively concentrated  state;  but  they  are  offensive  to  the 
senses  and  thus  give  warning  of  their  presence,  so  that 


EFFECTS  OF  ILLUMINATING  GAS  99 

there  is  less  danger  of  their  causing  serious  results.  Men 
can  accustom  themselves  to  much  larger  proportions  of 
hydrogen  sulphide  in  the  atmosphere  than  can  animals, 
but  continued  exposure  to  it  is  liable  to  give  rise  to  ver- 
tigo, headache,  slow  and  weak  pulse,  sweating,  and  loss 
of  strength. 

When  sewer-gas  or  soil-air  escapes  into  the  outer  air 
they  are  usually  soon  diluted  beyond  power  for  harm; 
)but  if  either  gains  access  to  closed  rooms  or  unventilated 
dwellings,  its  effects  upon  the  inmates  are  depressing  and 
decidedly  harmful.  In  either  case,  concentration  of  the 
impurities  may  cause  acute  symptoms,  such  as  vomiting, 
purging,  severe  headache  and  prostration.  Their  influence, 
however,  is  usually  insidious,  owing  to  dilution  with  the 
house-air;  and  the  more  common  symptoms  attributable 
to  them  will  probably  be  pallor,  languor,  frequent  head- 
ache, loss  of  appetite,  diarrhea,  impaired  health,  and 
often  chronic  anemia.  Children  especially  suffer  in 
nutrition,  and  with  them  febrile  attacks  may  be  frequent; 
but  with  all,  the  power  of  resisting  such  diseases  as 
typhoid  fever,  diphtheria,  etc.,  is  lessened  and  the  sus- 
ceptibility to  them  is  increased,  the  sickness  more  severe, 
and  the  convalescence  more  prolonged.  Indeed,  sewer- 
gas  and  soil-air  probably  aggravate  all  diseases. 

In  this  connection  Alessi  has  shown  that  when  small 
animals,  such  as  rabbits,  rats,  and  guinea-pigs,  have  been 
exposed  to  sewer-air  for  some  days,  by  far  the  larger 
majority  when  inoculated  with  only  a  small  quantity  of 
a  slightly  virulent  typhoid  culture  contract  the  disease  and 
die,  while  almost  none  succumb  of  those  treated  similarly 
in  every  way  excepting  by  the  exposure  to  sewer-air.  He 
also  showed  that  the  inoculations  were  more  deadly  when 
the  previous  exposure  to  the  noxious  gas  had  been  less 
than  two  weeks  than  when  it  exceeded  that  period,  indi- 
cating that  animals,  as  well  as  persons  accustomed  to  such 
contamination,  are  not  apt  to  manifest  the  symptoms  due 
to  it  so  rapidly  or  so  seriously  as  are  those  who  experience 
it  for  the  first  time — a  fact  well  known  to  all  observers. 


100  THE  ATMOSPHERE— AIR 

It  is  only  fair  to  say  that  these  experiments  of  Alessi  have 
apparently  been  controverted  by  other  observers;  but, 
whichever  may  be  correct,  the  truth  of  the  following 
quotation  doubtless  still  holds  good: 

"There  is  undoubtedly  a  poisonous  agency  at  work 
when  sewer-gas  is  inhaled,  which,  though  it  may  not 
directly  act,  yet  so  prepares  the  soil  that  the  system  is 
unable  to  resist  the  invading  organism  when  it  comes.  "^ 

1  Notter  and  Firth,  p.  159. 


CHAPTER  IV. 
VENTILATION  AND  HEATING. 

As  we  are  not  usually  able  to  destroy  the  impurities 
of  the  atmosphere  within  ojir  dwellings  as  rapidly  as  they 
are  produced,  we  have  recourse  to  ventilation  as  a  means 
for  their  dilution  and  prompt  removal.  We  must  not 
think,  however,  that  we  do  all  that  is  necessary  if  we  only 
renew  the  in-door  air,  for  unless  the  source  and  supply 
from  which  we  take  that  which  is  to  replace  or  dilute  the 
vitiated  air  be  pure  and  clean,  any  system  of  ventilation 
which  we  may  adopt  will  be  of  little  value. 

External  Ventilation. — External  ventilation  of  buildings, 
streets,  and  cities  is  of  importance,  then,  as  well  as  that  which 
relates  only  to  the  interiorof  dwellings,  workshops,  and  places 
of  assembly.  Numerous  investigations  and  statistics,  both 
here  and  abroad,  show  that  "the  health  of  a  town  largely 
depends  upon  the  width  of  the  streets,  the  general  height 
of  the  buildings,  and  the  amount  of  yard-space  at  the  rear 
of  each  which  separates  it  from  its  opposite  neighbor." 
It  is  also  difficult  to  overestimate  the  value  of  wide  streets, 
numerous  diagonal  ones  and  frequent  parks  or  open  spaces, 
especially  in  the  more  thickly  inhabited  portions  of  a  city. 
In  this  connection  we  may  refer  with  advantage  to  some 
work  of  Dr.  H.  S.  Anders,  of  Philadelphia,  in  which  he 
shows  that  "  the  number  of  deaths  from  phthisis  on  a  very 
wide  street  is  proportionately  small  compared  with  those 
on  almost  any  one  narrow  street,"  and  "that  there  is 
plainly  and  generally  a  high  mortality-rate  from  consump- 
tion associated  with  street  narrowness  in  not  a  small  part 
of  Philadelphia,  and  that  the  relation  between  a  high 
mortality  and  narrow  streets  is  a  positive  and  vital  one." 
His  statistics,  covering  a  period  of  fifteen  years,  show  that 

(101) 


102  VENTILA7I0N  AND  HEATING 

in  one  city  ward,  certainly  favored  as  to  location,  the 
ratio  of  deaths  from  phthisis  per  square  or  block  on  streets 
over  those  on  streets  under  forty  feet  in  width  was 
approximately  as  3  is  to  5. 

Internal  Ventilation. — As  regards  internal  ventilation,  it 
will  be  well  to  determine  at  the  outset  the  meaning  and  limi- 
tations of  the  term.  Parkes  says:  "It  will  be  desirable  to 
restrict  the  term  ventilation  to  the  removal  or  dilution,  by 
a  supply  of  pure  air,  of  the  pulmonary  and  cutaneous  exha- 
lations of  men,  and  of  the  products  of  combustion  of  lights 
in  ordinary  dwellings,  to  which  must  be  added,  in  hospitals, 
the  additional  effluvia  which  proceed  from  the  persons 
and  discharges  of  the  sick.  All  other  causes  of  impurity 
of  air  ought  to  be  excluded  by  cleanliness,  proper  removal 
of  solid  or  liquid  excreta,  and  attention  to  the  conditions 
surrounding  dwellings."  With  the  function  of  ventilation 
thus  limited,  it  will  not  be  necessary  to  make  provision 
for  such  an  abundant  supply  of  pure  air  as  might  other- 
wise seem  advisable.  It  is  evident  also  that  the  purity 
of  in-door  air  must  almost  always  be  relative  and  not 
absolute,  especially  in  a  climate  like  ours,  which  for  a 
considerable  portion  of  the  year  necessitates  warming  of 
the  air  and  some  consequent  economy  in  its  use. 

Since  the  importance  of  excessive  humidity,  high  tem- 
perature and  air-stagnation  as  factors  in  causing  much 
of  the  discomfort  and  depression  in  unventilated  places 
is  now  appreciated,  any  proper  definition  or  system  of 
ventilation  must  also  include  the  alteration  or  obviation  of 
such  conditions  and  the  adjustment  of  the  atmosphere  to 
a  state  most  favorable  for  physiological  comfort  and  well- 
being.  Wherefore,  the  present  tendency  is  to  consider 
the  condition  as  well  as  the  composition  of  the  atmos- 
phere as  of  prime  importance,  and  to  give  special  atten- 
tion to  the  former  in  planning  modern  ventilation  systems 
or  equipment. 

Considering  the  problems  of  atmospheric  improvement, 
however,  from  the  standpoint  of  composition  or  content, 
two  factors  must  be  determined  in  order  to  discover  the 


INTERNAL  VENTILATION  103 

quantity  of  air  desirable  and  consistent  with  the  require- 
ments of  good  ventilation  and  the  maintenance  of  health : 
(a)  the  extent  to  which  the  air  of  a  room  is  contaminated 
in  a  given  time  by  the  impurity  it  receives,  and  (b)  the 
limit  of  permissible  impurity  beyond  which  there  will  be  a 
possible  risk  or  detriment  to  health.  In  accordance  with 
the  above-mentioned  limitations  of  Parkes,  the  contamin- 
ating substances  will  usually  be  comparatively  few  in 
number,  but  the  same  factors  are  to  be  sought  in  the  case 
of  any  detrimental  substances  in  the  atmosphere  at  any 
time,  provided  their  source  or  cause  cannot  be  directly 
removed. 

Although  it  is  extremely  difficult  to  determine  quanti- 
tatively the  organic  matter  given  off  by  human  exhala- 
tion in  any  given  time,  the  carbon  dioxide,  as  has  been 
stated,  is  usually  exhaled  in  a  reasonably  constant  ratio 
with  it,  and  can  therefore  be  used  as  an  index  of  the 
amount  of  it  contaminating  the  air.  Taking  Pettenkofer's 
figures,  which  have  been  substantially  confirmed  by  other 
investigators,  viz.,  0.6  cubic  foot  of  carbon  dioxide  per 
hour  per  head  for  a  mixed  assemblage  at  rest,  0.7  cubic 
foot  for  adult  males,  and  increasing  amounts  according 
to  the  physical  work  done,  we  have  the  first  factor  (a)  of 
our  problem  determined  for  all  cases  where  the  products 
of  human  respiration  and  exhalation  are  the  only  contam- 
inants. 

In  establishing  the  limit  of  permissible  impurity — the 
second  factor  (b) — it  will  naturally  be  advisable  to  require 
that  the  supply  of  air  from  without  shall  be  sufficient  not 
only  to  be  thoroughly  consistent  with  health,  but  also  that 
there  may  be  no  perception  of  impurity  by  the  senses,  the 
air  of  the  room  remaining  apparently  as  fresh  and  pure  as 
that  out-of-doors.  To  this  end  de  Chaumont  made  a  large 
number  of  observations  (over  450),  and  found  that  as  long 
as  the  carbon  dioxide  due  solely  to  respiratory  impurity 
did  not  exceed  0.02  per  cent.,  the  in-door  air  did  not  differ 
sensibly  from  that  without,  but  that  when  the  respiratory 
CO2  reached  0.04  per  cent,  the  air  was  rather  *' close" 


104  VENTILATION  AND  HEATING 

and  the  organic  matter  was  becoming  perceptible  to  the 
sense  of  smell.  Subsequent  investigations  have  shown 
that  as  long  as  the  respiratory  CO2  does  not  exceed  0.02 
per  cent,  the  atmospheric  conditions  have  no  perceptible 
effect  upon  health.^  Consequently,  we  may  take  this 
amount  of  carbon  dioxide,  over  and  above  the  amount 
normally  present  at  the  time  in  the  outer  atmosphere,  as 
the  index  of  the  limit  of  organic  atmospheric  impurity 
from  human  bodies  permissible  in  ordinary  inhabited 
apartments. 

Having  now  the  two  factors  of  our  problem,  and  pro- 
vided there  are  no  other  sources  of  contamination,  it 
becomes  a  simple  matter  of  proportion  to  determine  the 
quantity  of  fresh  air  to  be  supplied  to  each  individual. 
The  equivalent  of  0.02  per  cent,  is  0.0002  cubic  foot 
of  carbon  dioxide  in  each  cubic  foot  of  air,  or  2  parts  in 
10,000.  In  a  mixed  assembly  at  rest  each  person  exhales 
0.6  cubic  foot  of  carbon  dioxide  per  hour.  Consequently, 
to  dilute  properly  this  respiratory  CO2  and  its  coincident 

O  fK 

organic  effluvia,  each  person  will  need  r^T^KF^or  3000  cubic 

feet  of  fresh  air  per  hour.  If  the  individuals  are  all  adult 
males,  or  if  they  are  working,  there  must  be  a  correspond- 
ing increase  in  the  air  supplied,  running  up  to  6000  or 
even  9000  cubic  feet  or  more  per  head  in  certain  laborious 
occupations.  This  is  the  theoretical  amount  of  pure  air 
necessary  for  good  ventilation;  but  in  practice  we  find 
that  we  can  get  along  in  safety  and  comfort  with  some- 
what less,  because  some  of  the  bodily  impurities  are 
almost  at  once  carried  away  and  out  of  the  room  by  the 
draughts  through  the  exits,  or  through  the  cracks  and 
crevices  in  the  walls  and  ceiling  which  act  as  exits,  and 
the  incoming  air  does  not,  therefore,  have  to  mix  with 
and  dilute  that  portion  of  the  impurities  that  is  so  imme- 

1  This  may  simply  mean  that  the  air  movement  is  sufficient  not  only 
to  obviate  the  concomitant  factors  of  excessive  heat,  humidity  and 
stagnation,  but  also  to  reduce  the  organic  matter  to  an  amount  or  pro- 
portion entirely  innocuous  to  the  human  economy. 


FACTORS  IN  VENTILATION  PROBLEMS         105 

d lately  removed,  and  also  because  the  currents  of  air 
stimulate  the  skin,  favor  evaporation,  cool  the  body  and 
obviate  stagnation,  which  is  one  of  the  depressing  factors 
already  mentioned.  In  other  words,  if  10  per  cent,  of 
the  vitiation  is  thus  directly  taken  away,  10  per  cent, 
less  of  pure  air  is  needed  to  dilute  the  remaining  contami- 
nants to  the  limit  of  permissible  impurity;  but  as  the 
quantity  and  the  consequent  velocity  of  the  incoming 
or  of  the  outgoing  air  diminishes,  less  and  less  of  the 
impurities  are  thus  directly  removed,  there  is  lessened 
physiological  reaction.  So  experience  teaches  that  almost 
the  entire  theoretical  supply  of  fresh  air  is  actually  needed 
in  practice  to  secure  satisfactory  results. 

Provision  must  also  be  made  for  sufficiently  diluting 
the  impurities  from  other  sources  of  vitiation  whenever 
they  are  present.  Although  combustion-products  generally 
accumulate  near  the  top  of  the  room  on  account  of  their 
high  temperature,  which  also  facilitates  their  escape,  we 
should  provide  at  least  1800  cubic  feet  of  air  for  each 
cubic  foot  of  gas  burned,  and  ten  times  as  much  for  each 
pound  of  oil  consumed. 

In  sick-rooms  and  hospitals  an  exception  must  also  be 
taken  to  the  assumption  that  0.02  per  cent,  of  carbon 
dioxide  be  taken  as  the  permissible  respiratory^  impurity, 
for  it  is  found  that  the  organic  matter  exhaled  from  the 
sick  is  much  more  offensive  than  that  from  the  well, 
and  is  noticeable  to  the  senses  when  the  respiratory  COj 
is  less  than  the  amount  permissible  for  those  in  normal 
health.  So,  at  least  one-fourth  or  more  must  be  added 
to  the  quantity  of  clean  air  necessary  for  the  healthy, 
and  a  good  rule  is  to  give  the  sick  as  much  as  possible, 
provided  it  be  properly  warmed  and  distributed. 

This  is  independent  of  the  modem  fresh-air  treatment 
of  many  diseases  which  is  to  be  looked  upon  as  a  thera- 
peutic rather  than  hygienic  measure;  nevertheless,  it  is 
difficult  to  make  a  sharp  distinction  between  the  ti^^o 
and  good  ventilation  of  hospitals  is  always  essential  and 
most  desirable. 


106  VENTILATION  AND  HEATING 

The  use  of  the  following  formula  will  often  be  of  ad- 
vantage in  solving  problems  relating  to  ventilation,  viz. : 

~=d,  where  e  represents  the  amount  of  carbonic  acid 

or  other  impurity  added  to  the  atmosphere  in  the  given 
time,  r  the  relative  ratio  of  the  impurity  in  parts  per 
cubic  foot,  and  d  the  delivery  or  volume  of  fresh  air  in 
cubic  feet.^  Example:  What  will  be  the  respiratory 
impurity  in  the  air  of  a  room  of  3000  cubic  feet  capacity 
which  has  been  occupied  by  three  men  for  two  hours, 
supposing  that  there  has  been  an  ingress  of  9000  cubic 
feet  of  fresh  air  in  that  time?    Here 

6=0.7  X  3  X2=4.2,  and  d  =3000+9000  =  12,000. 

0.035  per  cent,  of  carbon  dioxide. 

Before  considering  the  means  by  which  a  sufficient 
quantity  of  pure  air  may  be  supplied  to  buildings  and 
apartments,  it  will  be  well  to  note  the  following  restric- 
tions as  to  the  size  and  height  of  the  rooms.  If  a  room  be 
too  small,  the  air  therein  will  have  to  be  changed  often, 
the  velocity  at  the  inlets  will  be  increased,  uncomfortable 
draughts  will  be  created,  and  the  air  will  not  diffuse  itself 
so  thoroughly  throughout  the  room.  Experience  shows 
that  even  when  the  air  is  properly  warmed,  it  cannot  be 
changed  much  oftener  than  three  times  an  hour  without 
discomfort  to  the  occupants  of  the  room,  unless  the  ven- 
tilating apparatus  be  very  perfect  in  its  workings  and 
therefore  expensive.  Consequently,  as  we  take  3000 
cubic  feet  of  fresh  air  to  be  the  average  amount  required 
per  person  per  hour,  the  cuhic  space  per  individual  should 
be  at  least  1000  cubic  feet,  with  a  corresponding  increase 
where  the  occupants  are  all  adult  males,  are  all  at  work, 
or  are  in  hospitals. 

1  By  allowing  e  to  represent  the  total  contamination  per  hour,  and  r 
to  represent  the  limit  or  extent  of  impurity  in  any  given  case,  this 
formula  can  be  used  for  almost  any  other  ventilation  problem,  whatever 
may  be  the  contaminants  or  source  of  impurity. 


NECESSARY  QUANTITY  OF  AIR  107 

Again,  it  must  be  remembered  that  the  difficulty  of 
securing  equable  heating  and  ventilation  increases  with 
the  height  of  the  room  above  a  certain  limit,  and  that 
with  the  sick  especially  a  certain  amount  of  floor-space  is 
necessary,  both  for  the  separation  of  patients  and  conve- 
nience of  attendance.  Ten  or  twelve  feet  will  usually  be 
found  to  be  the  safe  limit  of  height  for  all  apartments 
intended  for  continuous  rather  than  temporary  occupation, 
and  consequently  there  should  be  a  minimum  allowance 
of  from  85  to  100  or  more  square  feet  of  floor-space 
per  head,  and  even  an  increase  above  this  in  w^orkshops, 
hospitals,  etc.  However,  there  is  no  objection  to  high 
ceilings  if  one  is  not  limited  as  to  floor-space,  pure  air- 
supply,  and  heat;  and  they  are  even  advisable  in  rooms 
where  many  lights  are  to  be  burned.  Again,  these  restric- 
tions regarding  cubic-  and  floor-space  do  not  necessarily 
apply  to  such  buildings  as  churches,  theatres,  etc.,  which 
are  occupied  for  only  a  comparatively  limited  time,  which 
can  be  thoroughly  flushed  out  after  use,  and  in  which  it 
is  evidently  impracticable  to  allot  to  each  person  the 
above  floor-area.  Yet  pains  must  be  taken  in  such 
assemblies  to  keep  the  atmosphere  pure  by  whatever 
means  are  necessary;  while  for  school-rooms  and  the  like 
there  must  be  extreme  care  that  the  pupils  are  not  over- 
crowded, and  that  they  have  a  full  supply  of  properly 
warmed  air. 

Any  correct  system  of  ventilation,  in  addition  to  the 
above  considerations,  must  take  into  account  the  source 
of  the  air  supplied,  the  distribution,  the  heating  or  cool- 
ing of  the  air  when  necessary,  and  its  relative  humidity. 

The  air  supplied  to  any  house  should  be  taken  from 
well  aboye  the  level  of  the  ground,  where  it  is  free  from 
contamination  and  is  constantly  changing,  and  not  from 
cellars  or  closed  areas,  where  the  atmosphere  is  stagnant 
and  full  of  impurities.  The  conduits  leading  to  the  heat- 
ing or  ventilating  apparatus  should  also  be  so  arranged 
that  they  may  be  frequently  and  readily  cleaned.  It  is 
well  to  have  them  covered  with  gratings  to  prevent 


108  VENTILATION  AND  HEATING 

objects  being  thrust  into  them,  and  in  some  cases  it  may 
even  be  advisable  to  filter  the  air  through  coarse  cloth 
or  fine  wire  gauze  to  free  it  from  dust  and  other  impurities. 
In  the  mechanical  system  of  ventilation  adopted  in  the 
chemical  laboratory  of  University  College,  Dundee,  the 
air  is  filtered  by  being  passed  through  jute  cloth  (light 
Hessian)  stretched  on  frames  seventeen  feet  long  by  four 
feet  wide.  In  this  case  the  presence  of  the  screen  actually 
increased  the  delivery  of  the  air  by  nearly  10  per  cent., 
probably  by  preventing  eddies.  The  screens  collected 
two  and  one-half  pounds  of  dirt  in  seven  weeks.  They 
last  about  a  year,  and  the  cost  is  about  2d  (four  cents)  a 
yard.^ 

The  air  may  be  kept  in  motion  and  efficient  ventila- 
tion secured  (1)  by  those  forces  more  or  less  continually 
acting  in  nature,  producing  natural  ventilation,  and  (2) 
by  these  in  combination  with  other  forces  set  in  action 
by  man,  giving  artificial  ventilation. 

Natural  Ventilation. — The  three  main  forces  of  natural 
ventilation  are  diffusion,  the  winds,  and  the  motion  caused 
by  the  difference  in  weight  of  volumes  of  air  of  different 
temperatures.  Diffusion  is  constantly  taking  place  between 
all  the  gaseous  constituents  and  impurities  of  the  air,  and 
even  effects  a  change  through  brick  and  stone  walls,  but  it 
alone  is  insufficient  to  keep  the  air  pure,  although  it  does 
much  to  further  this.  Moreover,  as  suspended  matters  are 
solid,  not  gaseous,  they  are  not  changed  or  removed  by 
it.  However,  the  action  of  this  force  should  not  be  ignored 
in  our  calculations  as  being  insignificant,  for  it  is  not  only 
continuous,  but  it  also  affects  the  whole  volume  of  the 
atmosphere  in  maintaining  its  uniformity  of  composition. 
"Roscoe  found  that  when  he  evolved  carbon  dioxide  in  a 
room,  the  amount  had  decreased  one-half  from  that  cause 
(diffusion)  in  ninety  minutes.  "^ 

As  the  rate  of  diffusion   is   inversely  as   the   square 

^  Stevenson  and  Murphy,  vol.  i,  p.  51. 
2  Notter  and  Firth,  p.  194. 


NATURAL  VENTILATION 


109 


roots  of  the  densities  of  the  gases  concerned,  the  inter- 
change goes  on  rapidly  when  there  is  much  difference  of 
temperature  between  the  in-door  and  outer  air,  and  also 
at  the  top  of  rooms,  where  the  warm  impurities  tend  to 
accumulate. 


Fig.  16. — Cowl  or  ventilator  for  aspiration. 


Winds  are  powerful  agents  for  ventilation,  and  a  slight 
breeze  passing  through  a  room  changes  the  air  therein 
many  times  in  the  course  of  an  hour,  and  carries  out  by 
its  force  many  of  the  solid  impurities  not  affected  by  dif- 
fusion. Wind  will  pass  through  walls  of  wood,  brick,  or 
stone,  although  its  progress  is  markedly  arrested  by  much 
moisture  in  the  walls  and  by  paper  or  plaster.  The  aver- 
age rate  of  movement  of  the  wind  is  considerable,  but 
the  disadvantages  in  utilizing  it  in  ventilation  are  the 


no  VENTILATION  AND  HEATING 

uncertainty  of  its  direction  and  velocity,  the  difficulty  of 
regulating  it,  and  the  fact  that  it  may  fail  us  at  a  time 
when  we  most  need  its  action.  In  winter  it  usually  has 
to  be  excluded  directly  from  our  houses,  because  a  velocity 
of  five  or  six  feet  per  second  is  not  comfortable  unless  the 
air  be  previously  warmed.  We  may,  however,  take  advan- 
tage of  the  facts  that  a  small  current  with  a  high  velocity 
will  set  in  motion  a  larger  volume  of  air,  and  that  wind 
blowing  across  the  top  of  a  tube  will  cause  an  upward 
movement  of  air  in  the  tube.  This  is  one  reason  why 
there  is  almost  always  a  draught  up  an  unused  chimney 
and  why  it  usually  acts  as  a  good  ventilating  outlet. 

To  utilize  these  perflating  and  aspirating  powers  of  the 
wind,  and  to  prevent  back-draughts  down  chimneys  and 
ventilating  pipes,  we  make  use  of  so-called  ventilators  or 
cowls  J  either  movable  or  fixed.  We  can  so  arrange  these 
that  the  force  of  the  wind  either  drives  air  into  the  building 
(perflation)  or  draws  air  out  of  it  (aspiration) .  Very  good 
systems  employing  these  have  been  put  in  operation,  the 
incoming  air  being  warmed,  when  necessary,  by  passing  it 
over  stoves,  steam  coils,  etc.,  and  they  are  especially  useful 
where  the  inner  air  is  colder  than  that  externally,  and 
where  artificial  methods  of  ventilation  dependent  upon 
heat  cannot  be  employed,  as  in  the  holds  of  ships,  deep 
basements,  etc. 

The  most  important  agent  in  natural  ventilation  is, 
however,  the  movement  produced  by  variations  in  the 
specific  gravity  of  air.  Although  the  wind  might  be 
included  under  this  head,  being  produced  by  the  same 
force,  the  air  is  moved  independently  of  the  wind,  espe- 
cially in  closed  buildings.  As  the  air  expands  when  heated, 
it  becomes  lighter,  volume  for  volume,  and  rises  because 
the  colder,  heavier  air  pushes  in  beneath  to  occupy  the 
space.  Now  in  all  inhabited  apartments  a  warming  of  the 
atmosphere  is  continually  taking  place,  not  only  by  means  of 
the  lights  and  heating  apparatus,  but  also  by  the  bodies  of 
the  occupants.  The  consequent  movement  is  therefore 
a  continual  though  not  necessarily  an  equable  one,  vary- 


WINDS  AS  VENTILATING  AGENTS  111 

Ing  as  it  does  with  the  temperature  of  the  out-door  air  and 
the  riumber  and  intensity  of  the  heating  agents  within. 
There  being  such  a  warming  and  movement  of  the  air, 
it  follows  that,  unless  a  room  be  perfectly  air-tight,  some 
of  the  apertures  will  act  as  inlets  and  others  as  outlets, 
and  the  quantity  flowing  out  of  the  room  will  be  prac- 
tically equivalent  to  that  flowing  into  it.  Therefore, 
though  this  force  may  not  be  so  powerful  or  efficient  as 
strong  winds  at  certain  times,  yet  being  more  constant, 
more  readily  determined  or  calculated,  and  more  controll- 
able, it  is  the  one  most  to  be  considered  in  arranging  a 
system  of  ventilation. 

To  determine  the  velocity  of  the  influx  or  outgo  of  air, 
we  make  use  of  the  law  that  a  fluid  passes  through  an 
opening  in  a  partition  between  two  volumes  of  the  fluid 
with  the  velocity  which  a  body  would  acquire  in  falling 
from  a  height  equal  to  the  difference  in  level'of  the  fluid 
on  the  two  sides  of  the  partition.  In  the  case  of  a  current 
of  air  we  substitute  for  the  difference  of  level  the  differ- 
ence in  pressure  on  the  two  sides  of  the  partition  or  open- 
ing, and  this  is  expressed  by  the  difference  in  temperature 
multiplied  by  the  difference  in  height  of  the  openings  of 
entrance  and  exit,  and  divided  by  491,  ^ir  representing 
the  expansion  of  the  atmosphere  in  volume  and  the  les- 
sening of  density  for  each  degree  (Fahrenheit)  of  rise  in 
temperature.    The  velocity  will  therefore  equal 


V 


(diff.  in  temp.)  X  (diff.  in  height). 
491 


Example:  What  is  the  velocity  of  the  current  in  a  chim- 
ney 40  feet  high,  the  out-door  temperature  being  20°  F. 
and  in-doors  70°  F.?    Answer: 


-v 


^?^-^ii?  =  8  X  2  +,  or  about  16  feet  per  aecond. 
491 


In  actual  practice  use  is  made  of  a  table  derived  from 
this  formula,  or  else  the  velocity  is  determined  directly 


112 


VENTILATION  AND  HEATING 


by  means  of  the  anemometer.  Allowance  must  be  made 
for  the  friction  of  the  air  against  the  sides  of  the  ducts 
and  against  itself,  amounting  to  from  one-fourth  to  one- 
half  of  the  theoretical  delivery,  according  to  the  length, 
size,  straightness,  etc.,  of  the  inlets  and  outlets.  The 
friction  will  be  inversely  as  the  diameter  of  the  openings 
and  directly  as  the  length  of  the  tubes;  the  shape  of  the 
openings  also  affects  it,  and  right  angles  diminish  the 
current  one-half.  Accumulations  of  dust  and  dirt  in  air 
conduits  greatly  lessen  the  velocity. 


Fig.  17. — Anemometer,  used  for  measuring  the  velocity  of  air-currents 
directly;  A,  slide  for  releasing  or  stopping  the  dial  hands;  E,  support 
for  attaching  the  instrument  to  a  staff  or  cane. 


The  average  velocity  multiplied  by  the  total  area  of  the 
inlets  or  outlets,  with  a  proper  allowance  for  friction,  will 
give  the  quantity  of  air  passing  through  the  rooms  or 
series  of  rooms  in  any  given  time. 

One  of  the  most  difficult  problems  in  natural  ventilation 
is  to  secure  a  uniform  distribution  of  pure  air  through  the 
rooms,  and  to  remove  the  impure  air  as  fast  as  the  pure 
air  is  supplied,  thus  preventing  its  mixing  with  the  latter. 
Certain  circumstances  always  make  the  question  compli- 
cated: the  size  and  number  of  inlets  and  outlets,  the  rate 


VOLOCITY  OF  AIR-CURRENTS  113 

and  direction  of  motion,  and  the  forces  acting  to  produce 
the  movement  must  always  be  subject  to  constant  change, 
and  must  thus  constantly  alter  the  result.  In  fact,  it  is 
practically  impossible  to  devise  a  plan  that  will  satisfy  all 
conditions  at  all  times,  and  the  best  that  can  be  done  is  to 
select  that  one  which  will  give  the  greatest  efficiency  and 
most  satisfactory  results  under  all  ordinary  circumstances. 
The  force  of  diffusion  will  always  act  as  long  as  there 
is  any  difference  of  temperature  and  any  communication 
between  the  exterior  and  interior,  and  no  special  attention 
need  be  given  to  it.  For  reasons  already  given,  we  cannot 
use  the  wind  continually,  but  we  should  employ  it  when- 
ever possible  by  opening  doors  and  windows,  on  account 
of  its  great  power  for  sweeping  out  solid  impurities  and 
"crowd-poison"  and  thoroughly  changing  the  air.  In  cold 
weather,  currents  from  windows,  etc.,  should  be  directed 
toward  the  ceiling,  so  that  they  may  be  diffused  and  par- 
tially warmed  before  reaching  the  inmates  of  the  room. 
Numerous  devices  have  been  suggested  for  introducing 
unwarmed  out-door  air  without  discomfort,  or  for  diffus- 
ing it  through  the  room:  among  these  may  be  mentioned 
perforated  bricks,  or  double-paned  windows,  valves, 
screws,  etc.  A  cheap  and  satisfactory  temporary  arrange- 
ment is  to  place  a  board  about  four  inches  wide  and  as 
long  as  the  width  of  the  lower  window-sash  beneath  the 
latter.  Or,  better,  have  a  light  frame  covered  with  fine 
netting  or  wire-gauze,  four  or  five  inches  wide,  made  to 
fit  above  the  upper  sash:  the  fresh  air  from  without  can 
now  enter  freely  between  the  upper  and  lower  sash,  being 
reflected  upward  by  the  inner  surface  of  the  glass  in  the 
upper  sash,  and  thus  mixing  with  warm  air  before  reaching 
the  occupants  of  the  room;  while  the  frame  at  the  top  of 
the  window  becomes  an  outlet  for  the  foul  air,  the  inter- 
ference of  the  netting  or  gauze  preventing  too  rapid  an 
outgo  and  consequent  loss  of  heat.  Another  excellent 
and  inexpensive  device  is  a  board  as  long  as  the  width  of 
the  window  and  eight  or  ten  inches  wide  which  is  placed 
so  that  its  lower  edge  rests  on  the  window  sill  and  it  slants 
8 


114 


VENTILATION  AND  HEATING 


inwardly,  being  held  in  place  by  V-shaped  pieces  attached 
to  the  window  frame  at  each  end.  When  the  window 
sash  is  raised  the  cool,  incoming  air  is  deflected  upward 
by  the  sloping  board  so  that  it  is  practically  unnotice- 
able  a  short  distance  from  the  window.  By  making 
suitable  grooves  in  the  end  pieces,  a  sheet  of  clear 
or  translucent  glass  may  be  substituted  for  the  board, 
thus  admitting  a  full  supply  of  light  and  improving  the 
appearance  of  the  device.     (Fig.  18.) 


Fig.  18. — Window  ventilator  with  translucent  glass  instead  of  board. 


But  in  a  climate  such  as  our  own,  and  in  all  cold  coun- 
tries, special  measures  must  be  taken  during  a  large  part 
of  the  year  for  warming  the  out-door  air  before  introduc- 
ing it  into  occupied  rooms. 

Where  we  intend  to  depend  most  upon  the  third  force  of 
natural  ventilation,  viz.,  the  movement  caused  by  unequal 
weights  of  air,  we  must  provide  other  openings  for  the 
entrance  and  exit  of  the  air  than  the  windows  and  doors, 
so  that  there  will  be  a  practically  constant  movement 
through  the  rooms  in  a  given  direction,  that  we  may  be 
sure  the  air  is  from  a  pure  source,  and  that  we  may  get 
the  utmost  service  from  our  appliances. 


VENTILATORS 


115 


There  is  considerable  difference  of  opinion  as  to  the  best 
locations  for  inlets  and  outlets,  and  as  the  conditions  are 
necessarily  different  in  every  case  and  so  many  factors 
are  to  be  considered,  it  is  difficult  to  lay  down  general 
rules.  It  should  be  an  aim,  however,  to  have  the  air 
well  distributed  throughout  the  room  or  rooms  and  to 
have  no  direct  draughts  from  the  inlets  either  upon  the 
occupants  or  to  the  outlets.     It  is  the  writer's  opinion 


Fig.  19. — Direction  of  air-currents  in  room  lighted  by  gas  and  heated 
by  open  grate. 


that  usually  the  outlets  should  be  located  near  the  top 
of  the  room,  owing  to  the  tendency  of  the  used  air  to  rise, 
and  because  in  unventilated  rooms  the  foulest  air  for 
some  time  after  its  contamination  will  be  found  nearest 
the  ceiling.  The  products  of  combustion  from  lights, 
etc.,  will  also  practically  all  be  in  the  upper  strata  of  air. 
(Fig.  19.)  If,  however,  provision  is  or  can  be  made  for 
a  constant  and  sufficiently  strong  aspirating  force  in  the 
outlet  ducts,  it  may  be  advisable  to  withdraw  the  used 


116 


VENTILATION  AND  HEATING 


air  from  near  the  floor  level  and  below  the  inlet  openings, 
though  not  in  too  close  proximity  to  them,  since  in  this 
way  a  more  thorough  distribution  of  the  incoming  air. 
and  a  greater  dispersion  of  its  contained  heat  are  secured. 
This  is  aptly  shown  in  the  illustration  depicting  the  cur- 
rents in  a  room  heated  by  a  ventilating  grate.  (Fig.  20.) 
This  principle  is  also  involved  in  the  well-known  Smead 
system  of  ventilation  and  heating,  which  still  further 
serves  economy  by  carrying  the  foul  air  beneath  the  floor 
of  the  room  from  which  it  is  taken,  thus  warming  the 


Fig.  20. — Direction  of  air-currents  in  room  heated  by  a  ventilating  grate. 

floor  with  some  of  the  heat  the  waste  air  yet  contains 
and  securing  the  utmost  benefit  and  service  from  the 
fuel.     (Fig.  21.) 

The  location  of  the  inlets  should  depend  on  the  tem- 
perature of  the  incoming  air;  if  it  is  cold,  it  should  be 
admitted  some  considerable  distance  above  the  floor, 
so  that  it  may  diffuse  and  be  partially  warmed  before 
reaching  the  inmates  of  the  room;  if  it  is  warmed,  it  may 
come  in  near  the  floor  or  below  the  middle  level  of  the 
room. 


DISTRIBUTION  OF  AIR 


117 


Where  much  fresh  air  is  required,  it  is  better  to  have  a 
number  of  inlets  and  outlets  than  one  large  one  of  each, 
as  the  distribution  is  then  more  certain.  The  total  area 
of  the  outlets  may  be  the  same  as  that  of  the  inlets,  as  the 
expansion  of  the  air  is  scarcely  sufficiently  great  to  require 
a  difference.  The  outlets  should  all  be  on  the  same  level; 
otherwise  the  highest  one  will  be  the  one  of  greatest  dis- 
charge, and  often  the  only  one,  the  others  possibly  acting 
as  inlets  and  drawing  air  from  an  impure  source.  As  the 
temperature  varies  from  time  to  time,  and  with  it  the  cur- 


Fio.  21. — Illustrating  the  Smead  system  of  ventilation. 


rent,  some  arrangement  is  needed  for  regulating  the  size 
of  the  openings  of  the  inlets  or  outlets  to  suit  the  varying 
conditions.  To  supply  3000  cubic  feet  of  air  per  head  per 
hour  a  velocity  of  5  feet  per  second  will  require  an  inlet 
opening  of  24  square  inches  for  each  person;  but  practi- 
cally it  is  better  to  have  a  larger  opening  than  this,  as  the 
above  velocity  is  uncomfortable  unless  the  air  be  well 
warmed.  Outlet  tubes  should  always  be  protected  from 
cold  and  kept  as  warm  as  possible. 
As  long  as  there  is  a  fire  in  a  grate  or  stove  connected 


118 


VENTILATION  AND  HEATING 


with  a  chimney  there  will  be  a  constant  upward  current 
in  the  latter;  and  the  area  of  the  chimney's  cross-section 
being  known,  and  the  velocity  determined  by  the  ane- 


FiG.  22  Fig.  23 

Outlet  ducts  warmed  by  stove-pipes. 

mometer  or  by  calculation,  as  already  indicated,  the 
amount  of  air  passing  out  of  the  room  in  this  way  may 
readily  be  determined.  In  this  connection  it  may  be 
stated  that  a  chimney  may  thus  act  as  the  only  outlet,  and 


LOCATION  OF  INLETS  AND  OUTLETS 


119 


all  other  openings  into  the  room  may  serve  as  inlets, 
especially  when  the  fire  is  brisk,  the  outgoing  current,  of 
course,  being  practically  equivalent  to  the  amount  of 


Fig.  24. — Waterbury  ventilating  stove,  showing  encircling  drum,   inlet 
for  out-door  air,  and  outlet  for  impure  air  into  chimney. 


incoming  air.  Moreover,  the  outgoing  current  may  be  so 
strong  as  to  overtax  the  capacity  of  the  inlets,  in  which 
case  more  or  less  of  a  vacuum  will  be  created  within,  so 
that  the  outside  pressure  may  cause  down  draughts  in  the 


120  VENTILATION  AND  HEATING 

chimney  from  time  to  time  and  a  driving  back  of  the 
smoke  and  gases  from  the  fire  into  the  room.  The  obvious 
remedy  is  to  efnlarge  the  inlet  area  by  opening  a  door  or 
window,  or  to  lessen  the  exit  draught  by  means  of  a 
damper  in  the  chimney.  On  the  other  hand,  the  inlets 
may  be  so  large  and  the  current  so  strong  that  the  air 
coming  into  the  room  cannot  be  properly  warmed,  in 
which  case,  again,  the  size  of  the  outlet  should  be  les- 
sened by  a  damper,  or  there  should  be  an  increase  in  the 
efficiency  of  the  heating  apparatus. 

When  we  wish  to  draw  air  from  distant  and  non-com- 
municating rooms,  the  ducts  may  be  led  into  a  chimney 
below  or  just  above  a  fire,  or,  better,  into  a  flue  or  shaft 
alongside  or  encircling  the  heated  chimney.  When  the 
exit  ducts  open  into  a  chimney  or  smoke-stack  the  draught 
is  greater  just  above  a  fire  than  below  it,  but  the  conduits 
should  not  enter  near  the  top  of  the  chimney,  for  there 
the  extracting  power  is  not  so  great  and  there  is  danger 
of  high  winds  blowing  smoke  and  foul  air  back  into  the 
rooms.  Outlet  flues  may  be  constructed  alongside  chim- 
neys that  are  being  constantly  used;  they  should  be  as 
smooth  as  possible  interiorly,  and  should  be  as  high  as  the 
adjoining  chimney,  to  avoid  down  draughts.  The  open- 
ings from  the  rooms  into  these  ducts  should  be  as  near 
the  ceiling  as  possible,  to  get  the  benefit  of  the  higher 
temperature  of  the  upper  strata  of  air,  unless,  as  previously 
indicated,  there  is  certainty  of  the  extracting  force  being 
constant  and  sufficiently  strong,  when  the  air  may  be 
taken  from  a  lower  level.     (Fig.  24.) 

Artificial  Ventilation. — Artificial  ventilation  is  that  which 
is  brought  about  by  the  intentional  application  of  the  above- 
mentioned  and  other  forces,  and  by  means  of  special  mechan- 
ical apparatus  and  devices,  in  contradistinction  to  natural 
ventilation,  which  may  act  independently  of  human  cogniz- 
ance and  intention.  It  consists  in  either  extracting  air  from, 
or  forcing  it  into,  a  room  or  building,  or  in  both  together. 
The  object  may  be  attained  by  heating  the  air  by  special 
apparatus  in  the  outlet,  or  by  warming  the  outlet  itself 


ARTIFICIAL   VENTILATION  121 

or  by  the  use  of  a  fan,  a  screw,  or  a  steam-  or  water-jet  in 
either  the  inlet  or  outlet. 

In  hospitals  and  other  places  where  a  constant  and  inde- 
pendent supply  of  heat  can  be  afforded,  extraction  shafts 
apart  from  chimneys  may  be  used.  These  extraction 
shafts  may  be  heated  by  fires,  steam  pipes,  or  steam-jets 
at  the  bottom,  or  by  steam  or  hot-water  pipes  coiled 
around  the  sides.  Some  system  like  the  following  is  some- 
times used  in  mines  where  large  quantities  of  air  must  be 
extracted.  There  are  an  entrance  and  an  extraction 
shaft;  large  fires  are  constantly  maintained  at  the  bottom 
of  the  latter,  the  air  is  drawn  down  the  former,  diverted 
through  all  parts  of  the  mine  by  partitions,  and  finally 
heated  and  carried  up  the  extraction  shaft. 

We  may  also  use  a  jet  of  steam  or  water  in  place  of 
heat  to  extract  air  through  a  shaft,  the  openings  of  the  foul- 
air  ducts  being  just  behind  the  jet.  It  is  said  that  a  steam- 
jet  may  thus  set  in  motion  over  two  hundred  times  its  own 
bulk  of  air.  Lastly,  fans  driven  by  electricity,  steam-  or 
water-power  are  employed  to  extract  the  air,  though  these 
are  usually  more  efficient  in  forcing  in  air.  One  of  36 
inches  diameter  at  600  revolutions  per  minute  will  propel 
or  extract  over  18,000  cubic  feet  of  air  per  minute. 

In  ventilation  by  propulsion  or  driving  in  air,  these 
large  revolving  fans  are  generally  used.  The  advantages 
of  this,  the  plenum,  system  of  ventilating  are  the  certainty 
as  to  the  direction  of  current  and  amount  of  air  supplied 
and  the  ease  with  which  the  quantity  can  be  altered  or 
measured  as  well  as  warmed;  also,  by  maintaining  a 
slight  excess  of  supply,  leakage  into  the  rooms  of  cold  or 
foul  air  from  without  is  prevented.  The  disadvantages 
are  the  high  cost  of  power  in  most  cases,  the  inconveni- 
ence or  danger  from  prolonged  stoppage  from  accidents  to 
the  apparatus,  and  some  difficulty  in  distributing  the  air. 
For  instance,  if  it  be  forced  in  through  small  openings  or 
at  too  great  a  velocity,  it  will  not  mix  properly  with  the 
air  of  the  room.  This  last  objection  can  usually  be 
obviated  by  giving  special  attention  to  the  size,  direction. 


122 


VENTILATION  AND  HEATING 


and  arrangement  of  the  inlet  flues,  and  the  relative  loca- 
tion, size,  etc.,  of  both  the  inlet  and  outlet  openings.  The 
increased  use  of  electric  motors  and  lowered  cost  of  run- 
ning them  will  doubtless  serve  to  make  this  system  of 
ventilation  more  common  in  the  near  future. 


Fig.  25. — Air  propeller,  with  electric  motor  attached. 


In  very  large  buildings  it  may  be  advisable  or  neces- 
sary to  combine  the  plenum  or  propulsion  with  the 
exhaust  or  vacuum  system,  using  power  fans  both  to  drive 
in  and  to  force  out  large  volumes  of  air.  In  this  way  an 
almost  ideal  ventilation  may  be  secured,  provided  the 
incoming  air  be  clean  and  be  sufficiently  warmed  by 
means  of  steam  or  hot-water  coils  or  radiators  (see  pages 
144  and  145). 

Parkes  and  Kenwood  summarize  the  essential  and 
practical  points  of  ventilation  as  follows: 


PLENUM  AND  VACUUM  SYSTEMS  123 

"1.  When  air  is  heated,  it  expands  and  tends  to  rise; 
when  air  is  cooled,  it  contracts  and  tends  to  fall. 

"2.  Cold  air  tends  to  enter  a  room  and  to  move  about 
very  much  as  water  would ;  and  this  holds  true  so  long  as 
the  temperature  of  the  fresh  air  remains  lower  than  that 
in  the  room. 

"3.  The  extent  of  inlet  provision  is  not  quite  of  the 
same  importance  as  that  for  the  exit  of  foul  air;  for  if 
foul  air  is  extracted  in  sufficient  quantities,  fresh  air  will 
enter  somehow  to  replace  it,  as  by  skirtings,  crevices  in 
doors  or  windows,  or  even  through  brick-work  in  walls. 

"4.  While  the  inlet  provision  for  fresh  air  should  aver- 
age 24  square  inches  for  each  individual,  several  small 
inlets  not  too  near  each  other  are  preferable  to  one  large 
one;  and  the  provision  of  inlet  areas  somewhat  larger 
than  those  of  exit  tends  to  minimize  draughts. 

"5.  Inlets  should  be  as  low  in  the  room  as  possible — 
i.  e.f  just  above  the  floor  (so  as  not  to  raise  the  dust) — if 
the  outside  air  is  warm  or  has  been  warmed  prior  to 
entry;  but  at  a  height  of  five  feet  or  more  if  the  outside 
air  is  cold:  otherwise  unpleasant  draughts  are  experienced. 
As  a  further  protection  against  unpleasant  draughts  when 
cold  air  is  admitted,  the  incoming  air  should  be  directed 
upward;  while  hot  air,  since  it  tends  to  rise,  should  be 
directed  downward. 

"6.  Outlets  should  be  as  high  as  possible,  and  prefer- 
ably close  to  or  in  the  ceiling;  and  they  should  have  their 
extractive  powers  maintained  by  means  of  heat  or  of  an 
exhaust  fan,  or  they  are  liable  to  act  as  inlets. 

"  7.  If  possible,  outlets  should  be  so  placed  that  vitiated 
air  is  drawn  toward  them  before  mixing  with  the  general 
air  of  the  room. 

"8.  The  tendency  for  fresh  air  to  take  a  direct  course 
to  the  outlets  must  be  overcome  by  judicious  selection  of 
the  positions  of  inlets  and  outlets. 

"9.  Methods  of  ventilation  devised  to  ventilate  crowded 
premises  are  generally  inefficient  unless  the  incoming  air 
can  be  warmed  in  winter  to  about  60°  F.;  for  efficient 


124  VENTILATION  AND  HEATING 

ventilation  by  cold  air  cannot  be  tolerated,  and  there  is  a 
great  tendency  among  workers  to  close  all  ventilating 
inlets. 

"10.  With  less  than  250  cubic  feet  of  space  for  each 
person,  ventilation  can  never  be  satisfactory  without  the 
aid  of  mechanical  force. 

"11.  The  source  of  the  incoming  air  should  be  consid- 
ered. It  should  not  be  borrowed  from  adjoining  rooms, 
but  taken  directly  from  the  outside.  One  great  advantage 
of  the  more  expensive  mechanical  system  of  ventilation  is 
the  fact  that  sufficient  air  can  always  be  obtained  from  a 
source  that  is  known  and  selected. 

"12.  Ventilation  dependent  on  the  extraction  of  foul 
air  is  more  convenient  and  satisfactory  than  that  in  which 
propulsion  is  mainly  relied  upon;  but  the  purity  of  the 
air  is  not  provided  for  so  easily. 

"13.  Warmed  air  forced  into  a  room  should  be  raised 
only  to  a  temperature  sufficient  to  prevent  a  feeling  of 
cold  (about  60°  F.).  More  highly  heated  air  is  often  felt 
to  be  overdry  and  unpleasant." 

HOUSE-WARMING. 

In  cold  countries  there  must  be  some  resort  to  artificial 
heat  in  the  winter  season,  and  as  this  subject  is  more  or 
less  inseparably  and  closely  connected  with  ventilation,  it 
may  be  appropriately  considered  at  this  time.  Cold  is 
depressing,  uncomfortable,  and  sometimes  dangerous  to 
the  young  and  aged  and  to  women  whose  habits  of  life 
keep  them  much  in-doors,  though  well-fed,  healthy  adult 
men  may  not  be  much  affected  if  accustomed  to  it.  In 
this  country  we  seem  to  need  a  higher  temperature  in  our 
houses  than  in  Great  Britain,  on  account  of  our  drier 
climate  and  especially  because  we  keep  the  atmosphere 
of  our  dwellings  much  too  dry;  evaporation  and  conse- 
quent cooling  of  the  body  take  place  more  rapidly  here, 
and  so,  while  they  are  accustomed  to  a  temperature  of 
from  60°  to  65°  F.,  we  find  from  65°  to  75°  F.  to  be  no 


HOUSE-WARMING  125 

more  than  comfortable.  If,  however,  the  relative  humidity 
is  maintained  at  from  50  to  60  per  cent.,  a  temperature 
of  68°  F.  or  even  lower  will  usually  be  found  quite  as  com- 
fortable and  more  healthful  than  a  much  higher  one  in  a 
dry  atmosphere.  A  low  relative  humidity  is  as  unhygienic 
as  one  too  high. 

It  needs  but  slight  investigation  to  determine  that  we 
practically  make  use  of  but  two  kinds  of  heat — radiant 
and  convected — in  the  warming  of  houses,  and  that  of 
these  the  latter  is  by  far  the  more  generally  employed  and 
the  more  economical.  Radiant  heat,  although  it  is  con- 
sidered to  be  the  more  healthful  as  it  warms  an  object 
directly  without  raising  the  temperature  of  the  intervening 
air,  has  the  disadvantages  of  utilizing  but  a  small  propor- 
tion of  the  fuel-value,  of  decreasing  directly  as  the  square 
of  the  distance  of  the  object  from  the  source  of  heat, 
and  of  thus  being  available  only  in  comparatively  small 
apartments.  Our  best  example  of  radiant  heat  is  that 
which  comes  from  open  fires,  though  any  highly  heated 
object,  as  a  stove,  gives  off  more  or  less  of  it. 

Heat  that  is  carried  from  one  place  to  another  by 
warmed  masses  of  air,  water,  or  steam  is  said  to  be  con- 
vected, and  because  of  the  economy  in  its  use  and  the  ease 
of  distribution,  especially  in  large  spaces,  it  is  the  kind 
most  generally  used.  Conducted  heat,  which  passes  frond 
molecule  to  molecule  of  the  conducting  substance,  acts 
too  slowly  to  be  available  to  any  extent  in  house-heating 
and  may  therefore  be  omitted  from  this  discussion. 

Just  here  it  may  be  remarked  that  under  present  con- 
ditions there  are  three  things,  any  two  of  which  we  may 
have  in  cold  climates  or  weather,  but  not  all  three  together 
except  in  rare  instances:  they  are,  good  ventilation, 
efficient  heating,  and  low  expense.  The  reason  for  this  is 
that  any  good  system  of  ventilation  necessarily  and  con- 
tinually carries  off  a  large  quantity  of  air,  and  the  heat 
it  contains,  which  latter  is  lost  for  warming  purposes, 
must  be  replaced  at  the  expense  of  more  fuel.  A.  heat- 
unit  cannot  be  used  at  the  same  time  to  produce  ventila- 


126  VENTILATION  AND  HEATING 

tion  and  to  warm  objects  other  than  the  air  it  keeps  in 
motion.  The  principal  aim,  then,  in  estabHshing  any 
system  of  combined  ventilation  and  heating  must  be  to 
introduce,  warm  and  carry  off  no  more  air  than  is  neces- 
sary for  the  requirements  of  good  ventilation  and  health, 
and  to  produce  the  heat  for  warming  this  air  and  the 
house  itself  as  economically  as  possible,  though  care  must 
also  be  had  to  secure  evenness  of  distribution,  absence  of 
uncomfortable  draughts,  etc. 

The  usual  appliances  for  house-heating  are  open  grates 
or  fireplaces,  stoves,  and  hot-air,  steam,  and  hot-water 
furnaces.  To  these  may  now  be  added  electrical  heaters, 
but  the  cost  of  maintaining  the  latter  prevents  their  use 
at  present  by  any  but  the  wealthy. 

Ordinary  grates  and  open  fireplaces  give  practically 
only  radiant  heat,  and  render  available  only  from  7  to 
12  per  cent,  of  the  fuel  efficiency.  They  also  heat  directly 
only  the  surfaces  facing  them  of  objects  in  the  room,  leav- 
ing the  remainder  cold,  and  by  reason  of  the  strong  cur- 
rent up  the  chimney  are  also  apt  to  bring  in  large  quantities 
of  air  from  without  that  has  not  been  properly  warmed, 
and  thus  to  cause  chilling  and  injurious  draughts.  Where 
there  is  some  additional  means  of  heating  the  air  before  it 
enters  the  apartment  and  where  the  chimney  current  is 
controlled  by  a  damper,  they  are  valuable,  not  only  for 
the  good  ventilation  they  thus  produce,  but  for  the  pleas- 
ing effect  of  the  exposed  fire  as  well. 

But  if  there  be  no  additional  or  accessory  heating 
apparatus,  such  a  fireplace  cannot  be  said  to  give  good 
ventilation,  even  though  large  volumes  of  air  pass  up  the 
chimney,  for  this  air,  entering  unwarmed  from  without, 
sweeps  across  the  floor  of  the  room  as  a  shallow,  cold 
layer  much  below  the  level  of  the  breathing  apparatus  of 
the  inmates;  while  the  more  or  less  contaminated  air 
above  this  cold  stratum  remains  undiluted  and  unchanged. 
(See  Fig.  19.) 

To  make  open  grates  more  effective  for  heating,  the 
sides  and  top  should  be  inclined  to  the  back  at  an  angle 


OPEN  GRATES  AND  FIREPLACES 


127 


of  135  degrees,  so  as  to  throw  as  many  heat-rays  as  possi- 
ble into  the  room;  the  fuel  surface  should  be  concentrated, 
and  there  should  be  a  damper  to  prevent  too  rapid  com- 
bustion and  too  much  heat  and  air  escaping  up  the 
chimney.  It  is  to  be  understood,  of  course,  that  the 
objects  warmed  by  the  radiant  heat  of  the  open  fire  do 
in  turn  give  convected  heat  by  warming  the  air  surround- 
ing them. 


^'S^CA^/^^ 


Fig.  26. — Jackson's  ventilating  grate.  The  outer  casing  is  cut  away 
to  show  space  and  surface  for  warming  the  incoming  air.  The  air  enters 
through  the  oblong  inlet  (a)  and  passes  to  the  register  opening  (6)  (in 
front)  between  and  around  the  five  smoke-pipes  (c)  above. 


If,  however,  the  back  and  sides  of  these  grates  be  sur- 
rounded by  a  space  through  which  air  can  pass  and  be 
warmed  by  the  heat  that  would  otherwise  be  wasted,  we 
shall  have  a  much  more  satisfactory  apparatus,  since  we 
thus  get  both  radiant  and  convected  heat  and  may  obtain 
from  25  to  35  per  cent,  of  the  fuel  efficiency.  (Fig.  26.) 
And  if  clean  out-door  air  be  led  into  this  air-space  and  thus 
warmed  before  entering  the  room,  the  ventilation  will  be 
greatly  improved  (see  Fig.  20),  other  inlets  will  be  unnec- 
essary, uncomfortable  draughts  will  be  avoided,  and 
there  will  be  sufficient  heat  provided  for  one  or  more 
apartments  of  moderate  size.    The  air-chamber  at  the 


128 


VENTILATION  AND  HEATING 


back  should  not  be  too  small,  and  there  should  be  as 
much  heated  surface  to  warm  the  incoming  air  as  possible. 
Stoves  utilize  a  considerable  percentage  of  the  fuel — 
75  to  80  per  cent,  or  more — but  do  not  remove  much  air; 
so  ventilation  has  to  be  provided  for  in  some  other  way 
and  is  apt  to  be  neglected.  Stoves  may  also  give  off  dan- 
gerous gases  and  products  of  combustion  if  not  properly 
cared  for  or  if  the  damper  in  the  stove-pipe  be  entirely 
closed.    There  should  be  as  much  surface  exposed  as  is 


/ 


Wh-e 
gauze 


X 


Da  mper 


...Jac/iet 


-w-n 


\ 


k 


ffesfv  A  if 


M        M 


Fig.  27. — Jacketed  ventilating  stove.     (Harrington.) 


possible  without  diminishing  the  combustion,  so  that 
there  may  be  increased  radiation  and  that  much  air  may 
be  warmed  moderately  rather  than  a  little  excessively. 
It  is  often  advisable,  especially  in  assembly-  or  school- 
rooms and  the  like,  to  surround  the  stove  with  a  sheet- 
iron  cylinder  extending  from  the  floor  toward  the  ceiling 
and  to  bring  in  between  this  and  the  stove  a  supply  of 
fresh  air  from  without.  This  air  becomes  heated,  and, 
passing  out  over  the  top  of  the  cylinder  or  drum,  gives  a 
plentiful  supply  of  convected  heat  and  greatly  improves 


STOVES  129 

the  ventilation.  (Figs.  24  and  27.)  A  suitable  outlet 
must,  of  course,  be  provided. 

Carbon  monoxide  and  other  gases  are  known  to  leak 
through  cast  iron  when  it  is  highly  heated,  so  that  stoves 
should  not  be  allowed  to  become  too  hot.  The  produc- 
tion of  carbon  monoxide  is  most  abundant  soon  after 
fresh  fuel  is  added  to  the  fire,  and  is  evidenced  by  the 
characteristic  blue  flame  above  the  coals. ,  If  at  this  time 
the  escape  of  this  gas  into  the  outer  air  is  prevented  by 
the  careless  or  accidental  closing  of  a  damper  in .  the 
stove-pipe  or  chimney,  it  is  prone  to  pass  through  the 
top  and  sides  of  the  stove  in  the  manner  indicated,  and 
to  cause  the  serious  and  fatal  results  so  often  reported. 
Therefore  it  should  not  be  possible  to  cut  off  com- 
pletely the  draught  from  any  coal-burning  stove,  nor 
should  it  be  materially  lessened  until  combustion  is  well 
under  way. 

Other  objections  to  stoves  that  are  allowed  to  become 
too  hot  are  the  excessive  dryness  of  the  atmosphere  which 
they  cause  and  the  unpleasant  odor  due  to  the  scorching 
of  floating  organic  substances  that  come  in  contact  with 
the  hot  iron. 

The  fuel  most  commonly  used  in  both  grates  and  stoves 
is  either  wood  or  some  kind  of  coal  (bituminous,  anthra- 
cite, or  lignite) ;  but  gas  or  oil  may  often  be  advantageously 
and  more  satisfactorily  employed  instead  of  any  of  these, 
since  the  heat  can  be  had  from  them  practically  instanta- 
neously, can  be  closely  regulated  in  quantity,  and  can  be 
promptly  checked  when  no  longer  desired,  and  since  there 
is  no  production  of  dust  or  ashes  in  the  room.  The  main 
objection  to  gas  is  that  for  large  rooms  or  prolonged  or 
continuous  heating,  it  is  usually  more  expensive  than  the 
other  fuels;  but  this  does  not  hold  good  for  small  rooms, 
nor  sometimes  for  isolated  apartments  or  where  warmth 
is  needed  only  temporarily;  and  it  is  very  probable  that 
before  long  fuel-gas  will  be — it  can  be  now — supplied  at 
rates  which  will  justify  a  much  more  extended  use  of 
such  fuel. 


130 


VENTILATION  AND  HEATING 


The  ordinary  kinds  of  gas-grates  and  gas-stoves,  espe- 
cially those  which  consume  the  gas  incompletely,  should 
all  be  constructed  with  flues  to  carry  off  directly  the 
products  of  combustion,  and  this  particularly  when  any 
large  quantity  of  gas  is  used.  Theoretically,  when  the  gas 
is  burned  in  a  properly  adjusted  Bunsen  or  "atmospheric" 
burner,  the  only  combustion-products  will  be  carbon 
dioxide  and  water,  the  former  of  which  is  rapidly  dif- 


FiG.  28. — Section  of  Backus's  portable  steam  radiator  for  use  with  gas. 


fused  into  the  outer  air,  as  has  been  shown,  and  is  not 
likely  to  be  harmful  in  any  quantities  thus  produced, 
while  the  aqueous  vapor  is  usually  beneficial  to  the 
atmosphere  rather  than  otherwise.  However,  it  seems 
that  in  practice  even  these  Bunsen  burners  may  some- 
times give  to  the  air  a  disagreeable  odor  (said  to  be  due 
to  the  formation  of  acetylene),  and  so  occasionally  need 
flue  connections. 
In  this  connection  it  may  be  interesting  to  describe  one 


GAS  GRATES  AND  STOVES  131 

form  of  gas-heater  which,  so  far  as  the  writer  knows,  is 
unique.  It  is  intended  not  only  to  consume  perfectly  the 
gas  it  uses,  giving  nothing  to  the  air  but  carbon  dioxide 
and  water;  but  also  to  destroy  by  fire  the  impurities  of 
the  atmosphere  of  the  room,  thus  doing  away  with  chim- 
neys or  flues  and  the  necessity  of  excessive  ventilation.  By 
a  peculiar  arrangement  a  continuous  and  large  current  of 
air  is  made  to  pass  through  the  flame,  thus  consuming 
the  impurities  whether  gaseous  or  solid.  The  heat  of  the 
burning  gas  is  also  used  to  convert  a  quantity  of  water 
into  steam,  which,  by  heating  the  containing  chamber 
or  coils  of  pipe  and,  in  turn,  the  atmosphere  surround- 
ing these,  warms  many  times  the  volume  of  air  possible 
to  heat  by  the  flame  alone.  In  addition,  the  humidity 
of  the  atmosphere  is  maintained  by  the  evaporation  of 
water  from  an  open  basin  beneath  the  fire. 

The  ordinary  openings  of  any  room  are  amply  sufficient 
to  allow  diffusion  of  the  excess  of  carbon  dioxide — one- 
half  escaping  in  this  way,  according  to  Roscoe,  within 
ninety  minutes — and  to  permit  the  ingress  of  enough  air 
to  supply  all  the  oxygen-needs  of  the  inmates  and  of  the 
fire  itself.  Experience  and  careful  experiments  seem  to 
show  that  the  claims  of  the  inventor  are  well  founded, 
and  that  the  apparatus  is  healthful  in  its  operation  and 
produces  no  harmful  effects  even  after  continued  use  for 
several  months.  At  any  rate,  there  seems  to  be  no  reason 
why  we  may  not  purify  the  air  by  fire  instead  of  by  dilu- 
tion and  removal,  the  methods  employed  in  the  hitherto 
described  systems  of  ventilation. 

Oil-stoves  are  now  used  quite  extensively,  and,  beside 
being  portable,  have  the  same  advantages  as  gas-stoves, 
viz.,  that  a  considerable  quantity  of  heat  may  be  had 
quickly  and  just  as  long  as  it  is  desired,  and  at  a  fairly 
moderate  cost.  The  combustion-products  necessarily  mix 
directly  with  the  atmosphere  of  the  room  and,  where 
reasonably  perfect  burning  is  had,  doubtless  consist  ol 
little  else  than  carbon  dioxide  and  water.  One  pound  of 
oil,  the  hourly  consumption  of  a  rather  large  stove,  will 


132  VENTILATION  AND  HEATING 

require  about  150  cubic  feet  of  air  for  its  complete  com- 
bustion, and  will  produce  about  25  cubic  feet  of  carbon 
dioxide. 

"We  do  not  think  that  the  experience  has  yet  been 
accumulated  which  would  fenable  us  to  speak  positively 
of  the  innocuousness  of  a  considerable  admixture  of  car- 
bonic acid  with  the  air  we  breathe;  but  the  knowledge 
that  in  hundreds  of  cases  oil-stoves  are  used  for  heating 
living-rooms  and  even  bed-rooms,  without  apparent  injury 
to  the  occupants,  makes  one  feel  fairly  confident  that  the 
products  of  the  complete  combustion  of  hydrocarbons  are 
not  injurious  when  mixed  with  such  an  amount  of  air  as 
is  sufficient  to  dilute  to  a  proper  degree  the  respiratory 
products.  .  .  .  Experiments  show  that,  provided  the 
combustion  of  the  oil  is  complete  and  that  the  ventilation 
is  sufficient  for  the  ordinary  effects  of  respiration,  the  use 
of  oil-stoves  for  heating  purposes  may  be  advantageously 
employed  in  both  day-rooms  and  sleeping-rooms.  The 
efficacy  of  oil-stoves  is  increased  by  placing  over  them 
a  diffuser  or  radiator,  so  as  to  prevent  the  heated  products 
ascending  direct  to  the  ceiling;  care  needs  also  to  be  taken 
that  only  the  better  kinds  of  mineral  oil  are  used;  if 
inferior  qualities  of  oil  are  burnt,  perfect  combustion  is 
more  difficult  to  obtain."^ 

The  above  remarks,  as  far  as  they  apply  to  the  healthful 
use  of  oil-stoves,  may  probably  be  used  with  equal  justice 
in  regard  to  gas-stoves,  provided  that  with  such  dilution 
their  products  give  no  obviously  harmful  or  disagreeable 
results. 

CENTRALIZED  HEATING. 

The  heating  apparatus  thus  far  described  is  such  as  we 
are  accustomed  to  employ  for  warming  the  air  of  a  single, 
or  possibly  of  adjoining  rooms.  Where  a  whole  dwell- 
ing or  other  large  building  is  to  be  heated,  it  will  usually 
be  of  advantage  to  do  this  from  one  point,  and  that  not 

1  Notter  and  Firth,  p.  228. 


HOT-AIR  FURNACES 


133 


in  any  of  the  living  apartments.  In  this  way  we  shall 
have  a  centralization  of  fuel,  both  unburned  and  burning, 
and  the  ability  to  derive  more  heat  from  it;  a  lessening 
of  the  labor  and  attention  bestowed  on  the  fires;  the  obvi- 
ation  of  much  dust,  dirt,  and  combustion-products  in 
living-rooms,  and,  presumably,  a  more  equable  and  satis- 
factory warming  of  the  whole  building.  From  such  a 
central  point  the  heat  is  distributed  by  hot  air,  hot  water, 
or  steam,  or  by  hot  air  in  combination  with  either  of  the 
other  two. 


Fig.  29. — Spear's  hot-air  furnace  (without  casing). 


Hot-air  Furnaces. — Hot-air  furnaces  supply  a  large 
amount  of  convected  but  no  radiant  heat.  There  is  a  very 
prevalent  opinion  that  they  are  not  healthful,  and  that 
wherever  possible  they  should  be  replaced  by  some  other 
means  of  heating.  But  when  properly  constructed  and 


134  VENTILATION  AND  HEATING 

cared  for,  a  hot-air  furnace  of  the  proper  size  is  not  only 
a  good  heater  but  also  a  powerful  ventilating  agent,  for 
the  large  supply  of  air  passing  through  it  into  the  rooms 
above  must  in  turn  find  an  exit  either  through  specially 
devised  outlets  or  through  the  innumerable  cracks  and 
crevices  around  all  doors  and  windows,  and  the  ventilation 
will  be  accordingly. 

One  frequent  source  of  trouble  is  too  small  a  fire-box, 
giving  insufficient  heating  surface  and  necessitating  too 
rapid  and  too  intense  combustion  of  fuel.  There  should 
be  a  considerable  expanse  of  surface,  never  too  highly 
heated,  so  that  large  volumes  of  air  will  be  moderately 
warmed  rather  than  small  quantities  overheated  and 
"  burned. '^  Air  too  highly  heated  is  very  dry  and  offen- 
sive to  the  senses ;  also,  by  taking  excessive  moisture  from 
the  body  through  the  skin  and  mucous  membranes  and  by 
exciting  glandular  activity,  it  increases  the  liability  to 
frequent  "colds"  and  congestions.  Moreover,  a  large 
quantity  of  air  moderately  warmed  will  perforce  be  car- 
ried to  all  the  rooms  of  the  house,  warming  them  equably 
and  driving  before  it  the  air  already  there :  whereas  a  much 
smaller  volume,  excessively  heated  by  the  same  or  even 
a  greater  amount  of  fuel,  will  make  its  way  along  the 
conduits  of  least  resistance  to  a  few  favorably  located 
rooms,  overheating  them  while  the  rest  of  the  house  is 
unwarmed,  and  any  satisfactory  natural  ventilation  is 
thus  prevented. 

All  joints  in  the  furnace  must  be  as  nearly  gas-tight  as 
possible  to  prevent  the  combustion-products  passing  from 
the  fire-box  or  smoke-flues  into  the  air-chambers  and 
thence  into  the  rooms  above. 

The  furnace  should  be  located  near  the  cold  side  of  the 
house — that  is,  the  side  on  which  the  prevailing  cold  winds 
impinge — for  it  is  said  to  be  as  difficult  to  drive  the  air 
ten  feet  against  the  wind  as  forty  or  fifty  feet  with  it. 
It  may  also  be  well,  if  the  basement  ceiling  is  low,  to  place 
the  ash-pit  below  the  level  of  the  basement  floor,  in  order  to 
give  sufficient  slope  to  the  air-ducts;  but  in  every  case  the 


HOT-AIR  PURNACES  135 

space  beneath  the  furnace  should  be  made  impervious  with 
cement  or  asphalt  to  prevent  the  drawing  in  of  soil-air. 

The  air-supply  should  not  be  taken  from  the  cellar, 
even  though  the  latter  be  apparently  clean  and  free  from 


Fig.  30. — llut-air  furnace,  ahuwiag  culd-uir  iuluL  and  huL-air  lluea.     Only 
one  of  the  lateral  branches  of  the  main  inlet  {A)  above  is  shown. 


contamination  with  soil-air,  but  should  come  from  a 
clean  source  out-of-doors,  well  above  the  ground-level 
and  from  the  direction  of  the  prevailing  winds.  The 
cold-air  duct  or  ducts  should  be  screened  at  the  entrance 


136 


VENTILATION  AND  HEATING 


to  prevent  the  admission  of  refuse  or  vermin,  should  be  ar- 
ranged to  permit  of  regular  cleaning,  should  have  a  damper 
to  regulate  the  supply  of  air,  and  should  have  a  cross-section 
equivalent  to  at  least  two-thirds  of  the  combined  sectional 
areas  of  the  hot-air  flues  leading  from  the  furnace.  The 
importance  of  a  large  air-inlet  cannot  be  too  strongly  em- 
phasized, for  upon  this  feature  may  most  depend  the  satis- 
factory action  of  the  furnace.  It  may  be  desirable  to  provide 
for  filtration  of  the  air  through  coarse  cloth  or  fine  wire- 
gauze,  especially  if  there  be  much  dust  in  the  incoming  air.^ 

To  lessen  friction,  the  hot-air  flues  or  ducts  should  be 
preferably  round  or  square  and  not  too  small  or  narrow  in 
cross-section;  and  for  the  same  reason  they  should  be  as 
direct  in  their  course  and  as  nearly  vertical  as  possible. 
They  should  be  covered  from  the  furnace  to  the  register- 
openings  with  asbestos  or  other  non-conducting  material 
to  prevent  the  loss  of  heat  that  otherwise  escapes. from 
them  into  the  cellar  and  between  the  partitions.  Lastly, 
their  register-openings  into  the  rooms  should  not  face  the 
windows  or  prevailing  winds,  unless  it  be  unavoidable,  for 
if  they  do  the  passage  of  warm  air  into  the  rooms  will 
often  be  almost,  if  not  completely,  checked. 

The  following  table,  from  Coplin  and  Bevan,  gives  the 
proper  size  for  hot-air  flues  and  registers: 

FIRST  FLOOR. 


Size  of  room  in 

cubic 

Size  of  pipe. 

Size  of  register. 

feet. 

If  round. 

If  oblong. 

If  round,   j       If  oblong. 

Less  than  1500 

7 

nches 

4X9  inches 

1 
9  inches   |   7  X  10  inches 

1500  to  2000      . 

8 

" 

4  X  12       " 

10       «           8  X  10       " 

2000  to  3000      . 

9 

« 

4  X  16       " 

12       " 

8  X  12       " 

3000  to  4000      . 

10 

4  X  18       " 

12       " 

9  X  14       " 

1  See  page  108. 


COLD-  AND  HOT-AIR  FLUES  137 

Economy  will  be  subserved  in  most  eases  by  taking 
care  to  burn  the  fuel  in  hot-air  furnaces  quite  slowly, 
since  in  this  way  larger  quantities  of  air  are  warmed  and 
more  satisfactorily,  and  there. is  also  less  waste  of  heat 
through  the  smoke-flues  and  up  the  chimney.  Moreover, 
it  is  the  experience  of  the  writer  that  by  working  the 
furnace  in  this  way  at  low  pressure,  so  to  speak,  the  air 
from  it  will  be  less  likely  to  become  too  dry,  nor  will  it 
need  the  addition  of  so  much  moisture,  something  essen- 
tially necessary  and  yet  most  often  neglected  where  com- 
paratively little  air  is  excessively  heated. 

The  amount  of  water  to  be  added  also  depends  upon 
the  humidity  and  temperature  of  the  out-door  atmosphere. 
When  the  latter  is  but  little,  if  at  all,  below  the  freezing- 
point  and  is  almost  saturated,  and  when  the  in-door  air  is 
but  moderately  warmed,  as  suggested,  the  lack  of  added 
moisture  may  scarcely  be  noticed ;  while  if  the  air  without 
be  at  the  same  time  dry  and  very  cold,  its  actual  content 
of  water  will  be  very  little,  and  much  added  moisture 
will  be  needed  to  make  it  either  comfortable  or  healthful, 
even  though  warmed  to  only  a  moderate  degree.^ 

"Concerning  the  need  of  insuring  a  normal  amount  of 
moisture  in  the  air  of  heated  buildings,  there  is  more  or 
less  difference  of  opinion,  but  the  weight  of  evidence  from 
a  medical  stand-point,  and  from  our  own  sensations,  points 
to  the  advisability  of  introducing  an  amount  of  moisture 
sufficient  to  bring  the  relative  humidity  of  the  air  to  50 
or  55  per  cent.  .  .  .  Air  at  25°  F.,  saturated  with 
moisture  and  then  heated  to  70°,  would  need  over  a  half- 
pint  of  water  in  every  thousand  cubic  feet  to  give  it  a 
humidity  of  65  per  cent.,  and  this  is  far  in  excess  of  the 

*  Most  modern  furnaces  have  a  water-pan  from  which  evaporation 
may  take  place  into  the  warmed  air,  but  the  filling  of  this,  when  left  to 
servants,  is  so  often  neglected  that  connection  with  the  water-supply 
of  the  house  by  means  of  a  float-valve  or  automatic  cut-off  would  better 
serve  to  secure  a  constant  supply.  Even  then,  these  water-pans  as  ordi- 
narily constructed  are  probably  inadequate,  especially  in  cold  climates, 
to  maintain  the  degree  of  humidity  desired,  and  additional  moisture 
should  be  provided  from  other  sources,  if  possible. 


138  VENTILATION  AND  HEATING 

capacity  of  the  ordinary  water-pan  of  the  furnace,  as  is 
seen  when  we  reckon  what  half  a  pint  per  thousand  cubic 
feet  means  in  the  course  of  a  day."^ 

Some  recent  tests  by  H.  M.  Smith,  of  Brooklyn,  show 
that  a  relative  humidity  above  50  per  cent,  and  a  tempera- 
ture of  about  65°  F.  is  most  healthful  and  comfortable. 
"  With  a  temperature  of  72  or  74  degrees  and  a  relative 
humidity  of  30  per  cent,  as  compared  with  a  room  at  65  to 
68  degrees  and  a  relative  humidity  of  about  60  per  cent., 
the  latter  seemed  the  warmer  and  more  comfortable."  On 
the  other  hand,  Ingersoll*'^  believes  that  in  cold  climates 


Fig.  31. — Humidifier.     The  cotton  wicking  shown  absorbs  water  from 
a  reservoir  below.     (Harrington.) 

the  ideal  in-door  humidity  for  a  temperature  of  about  70° 
is  from  40  to  45  per  cent.,  and  that  when  above  50  per 
cent,  the  condensation  in  cold  weather  is  unbearable. 

Prof.  Wilson,  of  Milwaukee,  says  further:  "About  25  per 
cent,  of  the  cost  of  heating  is  expended  in  raising  the  tem- 
perature from  60  to  70  degrees;  so  if  we  can  keep  com- 
fortable at  a  temperature  of  65  degrees,  we  shall  have 
saved  at  least  12.5  per  cent,  of  the  total  cost  of  heating." 

*  Harrington,  pp.  420  and  421. 

2  Journal  of  Home  Economics,  April,  1915. 


HOT-WATER  AND  STEAM-HEATING  139 

Hot-water  and  Steam-heating.— When  it  is  necessary 
to  carry  heat  for  a  considerable  distance  or  to  warm 
large  buildings  or  blocks  of  buildings  from  a  central 
point,  it  will  be  better  and  more  economical  to  employ 
hot  water  or  steam  as  the  heat-transmitting  agent,  on 
account  of  the  high  specific  heat  of  the  former  and  the 
great  amount  of  latent  heat  held  by  the  latter.  "It  is 
uneconomical  to  convey  heated  air  any  long  distance,  as 
the  amount  of  heat  conveyed  per  cubic  foot  of  air  raised 
to  any  practical  temperature  is  so  small  and  so  easily  lost 
in  transit.  On  this  account  Morin  considers  the  availability 
(of  hot-air  furnaces)  to  be  limited  to  a  horizontal  range 
of  40  to  45  feet  from  the  heating  apparatus."^ 

An  equal  quantity  of  heat,  viz.,  1  thermal  unit,  is 
required  to  raise  1  pound  of  water  or  50  cubic  feet  of  air  1 
degree  F.,  and  accordingly  water  will  carry  more  than  four 
(4.21)  times  as  much  heat  as  an  equal  weight  of  air  at  the 
same  temperature.  "Further,  a  greater  effect  is  produced 
when  water,  in  the  form  of  steam,  is  made  the  carrier  of 
heat,  because  1  pound  of  water  vapor  at  100°  C.  (212°  F.) 
will,  in  condensing  to  form  boiling  water,  give  off  suffi- 
cient heat  to  raise  the  temperature  of  5.36  pounds  of 
water  (or  4.21  X  5.36  =  22.5  pounds  of  air)  from  0°  to 
100°  C.  (32°to212°F.)."2 

Hot-water  heating  may  be  by  either  the  low-pressure 
or  the  high-pressure  system.  In  the  former,  large  pipes 
are  used,  and,  the  system  being  open  to  the  air  at  its  highest 
point,  the  temperature  of  the  water  can  never  be  much 
above  212°  F.  at  any  part  of  the  system.  The  water  circu- 
lates comparatively  slowly,  but  owing  to  the  large  volume, 
conveys  much  heat  from  the  furnace  to  the  places  where 
it  is  needed.  The  high-pressure  system  employs  small  but 
very  strong  pipes,  the  water  being  completely  enclosed 
from  the  outer  air,  wherefore  it  attains  a  high  temperature 
and  circulates  rapidly.    The  necessary  expansion  is  pro- 

'  Stevenson  and  Murphy,  vol.  i,  p.  117. 

'  Notter  and  Firth,  Treatise  on  Hygiene,  p.  231. 


140  VENTILATION  AND  HEATING 

vided  for  by  larger  pipes  partly  filled  with  air  at  the  top 
of  the  circuit.  The  maximum  temperature  is  regulated 
by  the  proportion  of  pipe,  usually  one-tenth,  exposed  to 
the  fire.  Either  of  the  hot-water  systems,  but  especially 
the  low-pressure  one,  requires  careful  planning  and  setting 
to  maintain  evenness  of  circulation;  and  when  the  latter 
is  complicated,  as  by  many  radiators  at  various  levels,  or 
where  a  number  of  circulations  have  to  be  supplied  from 
the  same  boiler,  it  may  be  very  difficult  to  maintain  an 
•  even  head  and  an  equable  distribution  of  heat  in  all. 
"If  properly  constructed  and  the  heating  planned  for 
when  the  house-plans  are  made,  this  hot-water  system  is 
probably  the  most  economical,  both  in  fuel  used  and 
repairs  demanded."^ 

Steam-heating  methods  are  usually  quite  satisfactory, 
not  only  because  of  the  large  quantity  of  heat  carried,  but 
also  since  a  rapid  circulation  is  readily  maintained  even 
under  adverse  circumstances.  The  size  of  pipe  used  will 
depend  on  the  extent  of  the  distribution,  but  the  caliber 
of  the  radiator  should  always  be  considerably  larger  than 
that  of  the  supply-pipes  in  order  to  favor  condensation 
and  the  consequent  liberation  of  latent  heat,  and  every 
facility  should  be  provided  for  the  speedy  return  of  the 
condensed  vapor  to  the  boiler.  Care  must  also  be  taken 
to  prevent  the  condensation  occurring  in  such  a  way  as 
to  cause  obstruction  to  the  flow  of  the  steam  and  the  dis- 
agreeable thumping  and  noise  that  result. 

With  either  steam-heating  or  hot-water  heating  the 
direct,  the  indirect,  or  the  direct-indirect  method  of 
radiation  may  be  used.  Of  these,  the  direct  method — 
that  is,  where  the  radiators  are  placed  in  the  rooms  to  be 
warmed — is  mdst  commonly  employed  in  dwellings  and 
other  buildings  of  moderate  size;  but  it  is  open  to  the 
objections  that  in  itself  it  does  not  bring  about  a  sufficient 
change  of  air,  that  the  necessary  inlets  and  outlets  for  the 
latter  are  rarely  provided,  and  that  when  present  they 

1  Coplin  and  Bevan,  p.  325. 


METHODS  OF  DISTRIBUTING  HEAT 


141 


are  independent  of  the  heating  system  of  the  house.  Of 
course,  these  objections  are  wanting  when  the  direct  is 
combined  with  the  indirect  method,  or  when  a  plentiful 
supply  of  pure  air  is  brought  from  without  and  is  warmed 
by  being  made  to  pass  through  the  radiators  (either  open 
or  enclosed  in  boxing)  before  diffusing  through  the  room. 
In  the  indirect  method  the  radiators  are  placed  outside 
of  the  room  in  suitable  and  convenient  enclosures,  into 
which  fresh  air  is  brought  from  out-of-doors,  and  from 
which  the  warmed  air  is  conveyed  by  suitable  conduits 


Fig.  32. — Indirect  radiation. 


to  the  respective  rooms  above.  The  direct-indirect  method 
locates  the  radiators  in  the  room,  but  encloses  them  and 
provides  inlets  to  the  boxing  from  without,  so  that  the 
entering  air  must  pass  over  the  heating  surface  and  be 
warmed  before  entering  the  room.  If  properly  arranged, 
both  the  indirect  and  the  direct-indirect  methods  should 
furnish  good  and  ample  ventilation,  the  incoming  warm 
air  pushing  the  used  air  of  the  room  ahead  of  it  through 
the  various  openings  in  the  walls  of  the  room.    Safety- 

1  Figs.  32, 33,  and  34  are  used  by  courtesy  of  The  American  Radiator  Co. 


142 


VENTILATION  AND  HEATING 


valves  on  steam  boilers  lessen  the  risk  of  explosions,  and 
automatic  thermo-regulators  make  it  possible  to  maintain 
a  practically  even  temperature  throughout  the  house  or 
building  at  all  times.  But  there  must  be  some  arrange- 
ment for  supplying  additional  moisture  to  the  warmed  air, 
just  as  with  hot-air  furnaces,  for,  contrary  to  the  opinion 
of  many,  neither  the  steam  nor  hot-water  systems  increase 
the  atmospheric  humidity. 

In  the  clinical  amphitheatre  of  the  Medico-Chirurgical 
College  of  Philadelphia  the  indirect  system  is  employed, 


Fig.  33. — This  illustration  shows  a  good  method  for  incasing  indirect 
radiation  and  also  suggests  a  simple  way  to  secure  rotary  circulation  of 
the  air  in  the  room  when  it  becomes  desirable  to  shut  off  the  out-door 
supply.  The  registers  in  the  floor,  however,  are  not  advisable,  as  they 
readily  collect  dust  and  dirt. 


the  details  being  as  follows:  The  out-door  air  is  brought 
from  near  the  roof-level  through  a  large  shaft  into  the 
cold-air  room,  where  it  is  moistened  by  a  spray  and 
whence  it  passes  through  a  dust-filter,  consisting  of  a 
double  layer  of  fine  wire-gauze.  Thence  it  passes  through 
tempering  radiators  (to  raise  the  temperature  partially) 
into  the  revolving  fan,  driven  by  its  own  engine,  whence 
part  passes  through  a  second  and  larger  radiator  to  be 
further  warmed,  and  part  below  the  latter,  the  two  cur- 
rents again  uniting  and,  after  mixing,  passing  through  the 
flues  into  the  amphitheatre  above.    In  this  the  tempera- 


AREA  OF  RADIATORS 


143 


ture  is  regulated  by  a  thermostat,  the  latter  governing  a 
damper  (not  shown  in  Fig.  35)  which  always  permits  the 
same  volume  of  air  to  pass  into  the  flues,  but  controls 
the  respective  proportions  of  heated  and  tempered  air,  so 
that  the  mixture  practically  does  not  vary  in  temperature. 
In  this  way  900,000  cubic  feet  of  air  at  a  fixed  tempera- 


FiG.  34. — Direct-indirect  radiation. 


ture  can  be  supplied  per  hour.  For  the  private  operating- 
rooms  the  system  is  the  same  except  that  the  tempered 
and  the  heated  air  are  not  mixed,  but  each  is  carried  by 
separate  flues  to  double  registers  in  the  operating-rooms. 
In  this  way  each  operator  can  have  the  temperature  that 
he  desires  in  his  room  at  any  time. 


144 


VENTILATION  AND  HEATING 


Another  excellent  method  is  to  use  the  plenum  system, 
and  to  warm  or  "temper"  the  incoming  air,  either  before 
or  after  it  passes  through  the  driving  fan,  to  a  temperature 
somewhat  below  that  desired  in  the  rooms,  in  which  steam 
or  hot-water  radiators  are  suitably  located.  The  air  will 
then  pass  from  the  inlets  more  or  less  directly  to  the  radia- 


FiG.  35. — Steam  radiators  and  blower  used  in  warming  the  clinical 
amphitheatre  of  the  Medico-Chirurgical  College  of  Philadelphia  by  the 
indirect  system.  (The  casing  of  the  radiators  is  not  yet  applied.)  Tem- 
pering radiator  at  left;   warming  radiator  at  right;   casing  of  fan  between. 


tors  and  be  additionally  warmed  by  them  before  rising 
above  the  lower  levels  of  the  room.  In  this  way  the 
regulation  of  heat  and  the  circulation  and  distribution  of 
the  fresh  air  are  much  improved,  and  there  is  less  like- 
lihood of  the  latter  going  directly  from  inlets  to  outlets. 

To  determine  the  amount  of  radiating  surface  needed 
for  any  room,  we  must  multiply  the  volume  of  air  to  be 


AREA   OF  RADIATORS  145 

heated  per  hour  by  the  difference  betweeji  its  temperature 
in  degrees  Fahrenheit  before  and  after  warming,  and 
divide  this  product  by  50,  the  quantity  of  air  in  cubic  feet 
raised  1  degree  F.  by  1  thermal  unit.  This  will  give  the 
number  of  heat-units  required  to  warm  the  air.  Then 
this  quotient  must  be  divided  by  the  dift'erence  between 
the  temperature  of  the  radiating  surface  and  that  of  the 
air  when  finally  warmed  multiplied  by  1.75 — the  number 
of  thermal  units  given  off  per  hour  by  1  square  foot  of 
hot-water  or  steam-pipe  for  each  Fahrenheit  degree  of 
heat  it  loses.  This  will  give  the  area  of  hot-water  or 
steam-pipe  required  to  w^arm  the  given  volume  of  air. 
Thus,  to  warm  6000  cubic  feet  of  air  per  hour  from  20° 
to  70°  F.  will  require 

6000  X  (70  -  20)       ^„„^  ^ 

^-- =  6000  heat-units. 

50 

and  if  the  temperature  of  the  surface  of  the  radiator  be 
200°  F., 

6000 


(200°  -  70°)  X  1.75 


26,37  square  feet,  which 


will  be  the  area  of  radiating  surface  required.  To  this 
must  be  added  at  least  one-half  square  foot  for  each 
square  foot  of  window-glass  and  for  each  square  yard  of 
outer  wall  exposed. 


10 


CHAPTER  V. 
WATER. 

Next  to  air,  water  is  the  most  important  of  all  sub- 
stances necessary  to  human  life.  While  it  has  been  often 
demonstrated  that  man  may  do  without  food  for  a  con- 
siderable length  of  time,  even  for  several  weeks,  he  can 
probably  not  survive  much  more  than  ten  days  without 
water.  Not  only  must  one  have  sufficient  to  supply  the 
internal  wants  of  the  body  and  to  replace  that  lost  by 
excretion,  evaporation  and  respiration,  but  from  a  sanitary 
point  of  view  a  plentiful  supply  is  also  needed  to  maintain 
cleanliness  of  bodies,  clothing  and  dwellings,  and  oftentimes 
to  remove  sewage,  excreta,  etc.,  from  the  vicinity  of  inhabi- 
ted places.  The  care  of  furnishing  water  in  abundance 
and  of  maintaining  its  purity  is  therefore  entirely  within 
the  domain  of  the  physician  and  the  sanitarian. 

Before  inquiring  into  the  sources  whence  we  obtain  the 
water  that  we  use,  it  will  be  well  to  know  what  amount  is 
required  by  the  body  for  its  daily  needs  and  how  much 
for  other  necessary  purposes,  so  that  we  may  be  able  to 
judge  not  only  whether  a  given  source  furnishes  pure 
water,  but  also  whether  it  gives  a  sufficient  supply  of  it. 

The  average  adult  should  take  from  70  to  100  fluid- 
ounces  per  day  for  nutrition  and  internal  needs  of  the 
body  alone — about  one-third  of  this  being  a  component 
part  of  the  food  and  the  rest  being  taken  in  as  drink.  The 
writer  is  of  the  opinion  that  the  average  person  does  not 
imbibe  enough  water  for  the  most  healthful  action  of  his 
tissues  and  organs.  Certain  it  is  that  in  most  cases  the 
plentiful  use  of  a  good  drinking-water  not  only  greatly 
favors  the  body  metabolism,  but  also  materially  assists  in 
(146) 


AMOUNT  NEEDED  DAILY  147 

the  flushing  out  and  carrying  away  of  the  various  wastes 
and  excreta  of  the  system. 

In  addition  to  this  we  must  supply  a  sufficiency  for 
cooking  and  for  washing  the  food,  body,  clothing,  house- 
hold utensils  and  parts  of  the  house  itself,  and  to  remove 
the  household  waste  and  sewage  through  the  drains  and 
sewers  provided  for  that  purpose.  Cleanliness  is  an  essen- 
tial requisite  for  the  preservation  of  health,  and  cleanly 
habits  should  be  inculcated  among  all  classes  of  people 
and  every  facility  provided"'for  removing  filth  of  all  kinds 
from  persons,  clothes  and  dwellings.  This,  of  course,  can- 
not be  done  without  an  abundant  supply  of  water. 

Experience  shows  that  about  25  gallons  per  head  per 
day  should  be  furnished  for  the  above  purposes,  and  as 
the  quantity  used  by  domestic  animals,  manufacturing 
establishments,  municipal  needs,  etc.,  must  be  added  to 
this,  50  gallons  or  even  more  per  capita  should  be  the 
daily  quota  for  a  community  wherever  it  is  at  all  possible 
to  secure  it.  And  though  a  supply  that  permits  of  excessive 
waste  may  be  inadvisable  and  expensive,  both  in  its  pro- 
vision and  on  account  of  increasing  the  cost  of  carrying  it 
away  after  use,  it  is  always  better  to  have  too  much  than 
too  little,  and  the  disadvantages  of  too  scanty  an  amount 
are  much  greater  than  those  of  one  too  large. 

It  should  be  stated,  however,  that  most  foreign  cities 
are  supplied  with  much  less  water  per  capita  than  is 
apparently  needed  by  the  municipalities  of  this  country, 
and  yet  they  seem  to  have  an  abundance  for  all  necessary 
purposes  and  the  requirements  of  public  health.  For 
instance,  London  has  an  average  daily  supply  of  about 
two-thirds  that  of  Philadelphia  with  one-third  the  number 
of  inhabitants;  while  Berlin,  which  has  about  the  same 
population  as  Philadelphia,  had  in  1905  an  average  daily 
supply  of  filtered  water  of  only  22  gallons  per  head,  all 
of  which  was  sold  to  consumers  by  meter,  but  to  which 
must  be  added  considerably  more  that  was  from  wells  and 
other  sources  and  was  exclusively  used  for  manufacturing 
purposes,  running  machinery,  etc.    Undoubtedly  the  quan- 


148  WATER 

tity  wasted  in  many  of  the  cities  in  this  country  is  exces- 
sive, and  the  cost  of  supplying  that  part  of  the  total  quota 
would  go  a  long  way  toward  improving  and  rendering 
pure  and  safe  the  remaining  part  that  is  absolutely  needed. 
Whether  the  compulsory  use  of  water-meters  is  the  best 
way  of  bringing  about  an  improvement  in  this  respect 
remains  to  be  determined;  but  it  is  also  a  question  whether 
our  larger  cities,  with  rapidly  increasing  populations,  can 
afford  to  continue  to  expend  the  money  necessary  to  purify 
the  enormous  and  increasing  quantities  of  water  daily 
supplied  to  their  respective  consumers.  With  the  obser- 
vance of  due  care  and  conservation,  a  daily  average  of  100 
gallons  per  capita  would  probably  be  found  to  be  a  reason- 
able maximum  for  almost  any  community. 

As  only  a  small  portion  of  the  quantity  indicated  above 
is  required  for  the  internal  needs  of  the  body,  it  has  been 
suggested  that  two  kinds  of  water  be  furnished  to  each 
dwelling — one  for  drinking  and  cooking  purposes  and  for 
the  washing  of  the  body,  to  which  especial  attention  as  to 
purity  should  be  given;  and  another  kind  for  all  other 
purposes,  its  composition  and  purity  being  disregarded, 
excepting  possibly  as  concerns  the  hardness.  This  would 
enable  the  authorities  to  furnish  a  water  purer  than  usual 
for  those  needs  wherein  purity  is  of  the  greatest  impor- 
tance, and  would  obviate  the  necessity  of  furnishing  pure 
water  abundantly  for  all  purposes;  but  the  plan  would 
necessitate  a  double  set  of  reservoirs,  mains,  distributing 
apparatus,  etc.,  thus  materially  increasing  the  cost;  and 
there  would  always  be  present  the  danger  of  the  careless 
or  ignorant  using  the  impure  water  for  bodily  needs,  thus 
increasing  the  risks  and  bad  results  that  we  wish  to  avoid. 
Therefore,  wherever  there  may  be  an  abundance  of  pure 
water  for  all  personal  and  domestic  purposes,  if  the 
authorities  but  take  pains  to  furnish  it,  it  will  be  best 
to  have  but  one  supply  in  dwellings,  and  this  as  pure 
and  abundant  as  money  and  the  ablest  sanitary  skill  can 
make  it,  though  there  may  be  little  or  no  objection  to  using 
a  different  water  for  factories,  stables,  city  functions,  etc. 

As  to  the  question  of  supply  through  meters,  it  may  be 


SOURCES  OF  WAT  Eli  149 

added  that  the  suggestion  has  been  made  that  the  regular 
charge  for  water  begin  only  after  a  certain  specified  amount 
per  month  per  capita  or  per  household  has  been  furnished 
free  or  at  the  lowest  possible  cost,  thus  doing  away  with 
the  objection  that  those  who  need  the  w^ater  most  for  per- 
sonal and  sanitary  uses  would  be  tempted  to  economize  too 
much  if  they  had  to  pay  for  all  they  consumed.  To  com- 
pensate for  this  it  might  be  wise  to  arrange  a  sliding  or 
increasing  price  scale  for  larger  quantities.  Whether  a 
city  could  afford  to  do  this,  would  have  to  be  carefully 
considered,  and  would  probably  depend  largely  upon 
local  conditions. 

Another  method  is  "to  assess  every  owner  of  premises 
where  water  is  used  (and  measured  by  meter)  a  certain 
moderate,  but  fixed,  sum  yearly,  even  though  w^ater  used 
at  the  regular  rate  per  thousand  gallons  does  not  call  for 
so  much  charge."  This  initial  sum  should  be  considerably 
less  than  the  rate  necessary  under  the  old  method,  and  in 
itself  would  be  an  inducement  to  the  introduction  and  use 
of  meters.  Any  water  used  in  excess  of  the  volume  repre- 
sented by  this  primary  charge  is,  of  course,  to  be  paid 
for  at  the  regular  meter  rate. 

Experience  shows  that  meters  greatly  reduce  the  total 
consumption  of  water,  since  it  is  to  the  direct  advantage 
of  each  consumer  to  check  reckless  waste  on  his  own 
premises,  which  duty  is  otherwise  neglected  because  it 
does  not  affect  the  yearly  charge  and  cost  of  water  to  him. 
Meters,  wherever  used,  seem  to  have  materially  reduced 
both  the  cost  of  water  to  the  consumer  and  the  cost  of 
supplying  it  on  the  part  of  the  city  or  other  owners  of  the 
water- works,  and,  so  far  as  the  writer  knows,  no  city  or 
community  that  has  once  installed  a  meter  system  has 
discontinued  their  use. 

SOURCES  OF  WATER. 

Practically,  all  drinking-water  has  at  some  time  or 
other  fallen  upon  the  earth  from  the  atmosphere  in 
the  form  of  rain,  hail,  snow,  or  dew;  but  when  we  speak 


150 


WATER 


of  its  source  we  have  reference  rather  to  the  immediate 
place  or  locality  from  which  we  collect  it  for  use.     The 


Fig,  36. — Cistern  and  filter  installation.  Approximate  cost,  S150. 
A,  Hogshead  or  large  tank;  B,  tight-cover;  C,  wire  screen;  D,  |-inch 
2-way  rain  cock;  E,  |-inch  union;  F,  |-inch  brass  or  galvanized  pipe, 
perforated;  G,  tight  overhanging  cover;  filter  box  may  be  wood,  iron, 
brick,  concrete,  or  4  feet  of  large-size  vitrified  pipe;  H,  24-inch  layer 
fine  sand;  /,  6-inch  layer  well- burned  wood  charcoal  size  of  wheat  grains; 
J,  2-inch  layer  of  gravel  size  of  a  small  pea  to  give  support  and  drain- 
age; K,  1-inch  2-way  rain  cock  with  1  branch  piped  to  waste;  L,  suction 
pipe;  M,  cistern,  side  walls  6  to  10  inches  thick;  A'',  1-inch  overflow;  O, 
sump  or  catch  basin;  P,  emergency  overflow;  Q,  screw  cap  (remove  cap 
and  attach  hand  pump  when  cleaning  cistern);  R,  waste  pipe;  S,  swing 
check  valve;  T,  screened  ventilator.  When  starting  operation,  waste 
the  first  water  filtered;  throttle  cocks  D  and  K  to  give  the  desired  low 
rate  of  filtration;  maintain  water  level  above  sand  layer,  thus  protecting 
the  surface  film  of  mud.  (Water  System  for  Farm  Homes,  U.  S.  Depart- 
ment of  Agriculture,  Farmers'  Bulletin,  p.  941.) 


rain  on  reaching  the  earth  is  disposed  of  in  three  ways: 
part  at  once  evaporates  and  goes  back  to  the  atmosphere, 
part  flows  off  according  to  the  slope  of  the  ground  and 


RAIN-WATER  151 

collects  in  pools  and  streams,  and  part  sinks  into  the 
soil.  The  ratio  which  these  three  portions  bear  to  one 
another  depends  on  the  time,  place,  character  of  soil, 
amount  of  rainfall,  etc.  Consequently,  we  may  classify 
the  sources  of  potable  waters — as  Leffmann  does — as 
follows:  rain-water,  collected  immediately  as  it  falls  in 
the  form  of  rain,  dew,  snow,  etc.;  surface-water,  collected 
in  ponds,  lakes,  streams,  etc.,  and  in  free  contact  with  the 
air;  subsoil-  or  ground-water,  derived  mainly  from  the 
rain-  or  surface-water  of  the  district,  but  which  percolates 
and  flows  through  the  subsoil  and  is  therefore  not  exposed 
directly  to  the  atmosphere;  deep-  or  artesian-water,  which 
is  separated  from  the  ground-water  of  the  district  by  one 
or  more  practically  impermeable  strata,  and  which  accu- 
mulates at  a  considerable  depth  below  the  surface.  Springs 
are  the  result  of  the  out-cropping  of  water-rbearing  strata 
below  the  level  of  the  water-line  in  them,  and  furnish 
either  subsoil-  or  artesian-water,  according  to  the  kind 
contained  in  the  respective  strata. 

Rain-water  is  theoretically  the  purest  at  our  command, 
but  in  reality  it  takes  up  many  impurities  from  the  air  in 
its  fall,  especially  in  the  neighborhood  of  human  habita- 
tions and  communities,  and  by  the  time  it  reaches  the 
earth  contains  ammonia,  nitrous  and  nitric  acids,  and,  in 
towns,  sulphurous  acid,  soot,  many  bacteria  and  other 
microscopic  plants.  Moreover,  and  especially  after  con- 
tinued dry  weather,  the  collecting  surface  upon  which  it 
falls  is  apt  to  be  covered  with  dust  and  impurities  of  all 
kinds,  which,  being  taken  up  by  the  rain-water,  tend  to 
make  it  unfit  for  use.  But  if  there  be  some  arrangement 
for  turning  aside  the  first  portion  of  the  rain,  it  contain- 
ing the  most  of  the  impurities,  and  if  the  remainder  be 
filtered  and  stored  in  proper  receptacles,  the  water  may  be 
of  excellent  quality. 

The  main  objection,  however,  to  the  sole  use  of  rain- 
water is  that  dependence  is  placed  upon  a  very  uncertain 
source,  and  one  which  is  especially  apt  to  fail  when  an 
increased  supply  is  most  needed.     The  average  rainfall 


152 


WATER 


in  Philadelphia  is  about  39  inches  per  year;  in  very  wet 
years  it  is  about  one-third  more,  and  in  very  dry  years 
about  one-third  less  than  the  annual  average.  Each  inch 
of  rainfall  gives  4.67  gallons  per  square  yard  of  area  on 
which  it  falls,  equivalent  to  22,617  gallons  per  acre. 
Allowing  60  square  feet  of  collecting  surface  per  head 
and  estimating  the  loss  by  evaporation,  etc.,  at  20  per  cent., 
an  annual  rainfall  of  30  inches  would  give  only  about  2 
gallons  per  head  per  day,  or  just  about  sufficient  for 

Movable  covering  stone.  Paving.  Level  of  ground. 

W/7Z!^>///////////y////////////////^^?i^:=r^^ 


Fig.  37. — A  simple  filter  for  rain-water.    (Notter  and  Firth.)  ^ 

drinking  and  cooking  purposes,  and  none  for  the  other 
needs  of  the  household. 

Rain-water  may  be  collected  from  roofs  or  from  a  plot 
of  ground  paved  for  the  purpose  with  slate  or  cement,  and 
be  led  by  proper  conduits  to  a  cistern.  It  should  be  filtered 
before  passing  into  the  cistern  (Figs.  37  and  38),  while  the 
cistern  itself  should  be  such  as  to  give  no  unpleasant  taste 


^  Fig.  37  illustrates  a  filter  for  an  underground  cistern.  One  of  similar 
construction  can  be  readily  made  for  cisterns  above  ground,  the  latter 
being  always  preferable. 


RAIN-WATEH 


153 


or  injurious  substance  to  the  water,  should  be  so  situated 
that  it  will  receive  no  rubbish  or  impurities  and  that  the 
water  may  be  kept  cool,  and  should  be  cleaned  regularly 
and  sufficiently  often  to  keep  the  water  sweet  and  whole- 
some. As  rain-water  contains  considerable  carbon  dioxide 
and  other  gases,  its  solvent  powers  are  increased,  and 
cisterns  should  not  be  lined  with  lead,  copper,  zinc,  or  iron, 
lest  these  metals  be  taken  up  by  the  water  and  produce 
harmful  results.    These  remarks  do  not  apply  to  the  so- 


1 


L. 


13Z 


TOP  V/£kV 


LONGITUDINAL    SECTION. 


Fig.  38. — Cistern  filter  of  concrete  and  stone.     (Bulletin  No.  57  of  the 
U.  S.  Department  of  Agriculture.) 

called  rustless  iron  now  much  used;  but  galvanized  iron 
should  not  be  used,  as  it  may  give  up  zinc  to  the  water. 
Cement  should  also  be  used  in  lining  brick  or  stone  cisterns 
instead  of  ordinary  mortar,  as  the  latter  may  add  lime  to 
the  water  and  render  it  hard. 

Underground  cisterns  for  storing  rain-water  should  be 
avoided  where  possible,  since  they  are  liable  to  soil-air  or 
sewage  contamination  unless  absolutely  air-  and  water- 
tight. Nor  should  the  overflow  pipe  from  a  cistern  open 
into  a  soil-pipe  or  sewer-pipe  or  drain,  but  always  into 


154  WATER 

the  open  air,  since  water  is  very  prone  to  absorb  the  vari- 
ous gases  with  which  it.  comes  in  contact  and  the  sewer- 
air  may  readily  contaminate  the  entire  contents  of  the 
cistern. 

Rain-water  is  especially  valuable  for  cooking  and  wash- 
ing on  account  of  its  softness,  water  being  called  "hard" 
when  it  contains  an  excess  of  the  salts  of  calcium  or 
magnesium  in  solution.  Hardness  due  to  the  presence 
of  calcium  bicarbonate  is  said  to  be  temporary,  because 
it  disappears  when  the  water  is  boiled,  one  molecule  of 
carbon  dioxide  being  driven  off  by  the  heat  and  leaving  the 
insoluble  calcium  carbonate  behind.  Hardness  due  to  many 
of  the  other  salts  of  calcium  and  magnesium  is  called  per- 
manent, because  it  is  not  removed  by  boiling.  In  cooking 
with  water  temporarily  hard  the  chalk  is  precipitated  upon 
the  sides  and  bottom  of  the  vessel,  and,  being  a  non-con- 
ductor, prevents  the  passage  of  heat  and  thus  wastes  fuel. 

Hard  water  may  also  prevent  the  proper  softening  of 
certain  foods,  such  as  peas  and  beans,  in  cooking.  In 
washing  and  laundry  work  the  calcium  and  magnesium 
salts  unite  with  the  fatty  acids  of  the  soap  and  prevent 
the  formation  of  a  lather;  for  instance,  one  grain  of  chalk 
destroys  the  efficiency  of  about  eight  grains  of  soap.  As 
we  do  not  call  a  water  hard  unless  it  contains  more  than 
ten  grains  of  chalk  or  its  equivalent  per  gallon,  and  as 
rain-water  rarely  contains  more  than  one-half  grain  per 
gallon,  it  is  easily  understood  why  the  latter  is  so  valuable 
in  the  kitchen  and  laundry. 

Surface-waters. — A  water-supply  taken  from  rivers  or 
smaller  streams  not  polluted  by  the  refuse  and  sewage 
from  towns,  factories,  or  cultivated  farm-lands  higher  up 
the  stream,  may  be  fairly  pure  and  safe  to  use.  The  best 
water  of  this  kind  will  be  from  hilly  and  uninhabited, 
uncultivated  tracts,  with  many  small  streams  fed  by  con- 
stant springs  and  uniting  to  form  rapid  creeks  and  rivers. 
Such  water  may  be  tinged  slightly  with  vegetable  or 
mineral  matters,  but  in  general  such  coloration  is  harm- 
less.   For  storage,  dams  may  be  thrown  across  convenient 


SURFACE-WATERS  155 

valleys,  thus  impounding  the  water  and  at  the  same 
time  exposing  it  to  the  oxidizing  and  aerating  influence 
of  the  atmosphere  and  allowing  the  solid  impurities  to 
settle  to  the  bottom.  Small  lakes  or  ponds  may  be  util- 
ized to  add  to  supplies  of  this  kind,  provided  they  be  not 
stagnant  nor  have  much  decaying  matter  along  their 
baiiks. 

On  the  other  hand,  water  from  a  stream  which  has 
received  the  sew^age  from  a  village  or  town  of  any  con- 
siderable size,  or  the  refuse  of  factories,  or  the  drainage 
from  large  tracts  of  cultivated  land,  should  be  considered 
as  at  least  suspicious.  River-waters  are  generally  hard 
and  may  contain  any  of  the  minerals  in  the  soils  which  they 
drain  or  over  which  they  pass;  but  the  great  danger  is 
from  impurities  of  animal  origin  poured  into  them  along 
their  course. 

It  is  not  safe  to  depend  altogether  on  the  self-purifica- 
tion of  sewage-contaminated  rivers,  as  was  formerly  done, 
though  a  considerable  portion  of  the  sewage  and  filth 
undoubtedly  is  removed,  part  by  oxidation  by  the  air  in 
the  water,  especially  in  streams  flowing  over  dams,  rapids, 
etc.;  part  by  subsidence  or  deposition  along  the  banks; 
part  by  fish  and  animalculse,  and  much  by  the  myriads 
of  saprophytic  bacteria  which  such  waters  contain.  If 
no  additional  pollution  is  added,  what  is  left  unchanged 
by  the  above  purifying  agencies  is  still  further  diluted 
by  the  supplies  of  pure  water  that  every  stream  receives 
from  springs  along  its  banks  and  in  its  bed  and  from 
tributary  streamlets,  so  that,  though  the  water  may  never 
be  so  pure  as  it  was  originally,  it  may  possibly  become  or, 
by  proper  filtration  or  other  treatment,  be  made  a  safe  and 
usable  water.  But  where  the  proportion  of  filth  exceeds 
a  certain  percentage,  and  especially  where  sewage  is  being 
constantly  added,  the  contained  oxygen  is  rapidly  used 
up  and  oxidation  ceases,  fish  and  animalculse  cannot  live 
in  the  water  for  lack  of  sufficient  oxygen,  and  though 
the  heavier  and  larger  particles  of  the  sewage  sink  to  the 
bottom  or  stick  to  the  sides,  they  are  stirred  up  and  set 


156 


WATER 


in  motion  by  any  increase  in  the  velocity  of  the  current. 
The  only  remaining  agents  active  in  the  destruction  of  the 
foul  matter  are  the  bacteria,  but  in  themselves  they  are 
often  insufficient  for  the  task,  and  the  water  thus  polluted 
is  unsafe  for  use.^    (See  Figs.  39,  40,  and  42.) 

The  greatest  danger  from  sewage  contamination,  how- 
ever, is  that  it  may  at  any  time  add  to  the  water  the 
germs  of  infectious  disease,  which  multiplying  rapidly 
and  not  being  surely  removed  or  destroyed  by  the  ordinary 
agents  or  methods  of  water-purification,  greatly  increase 
the  risks  to  health.     It  often  fortunately  happens  that. 


Fig.  39. — Outcropping  of  water-table.    (Harrington.) 


owing  to  the  hostility  of  the  saprophytic  bacteria  of  the 
water,  or  to  the  presence  of  certain  chemical  substances,  or 
to  other  unfavorable  conditions,  as  of  temperature  and  the 
like,  these  pathogenic  organisms  do  not  multiply  so  rapidly 
as  they  otherwise  would,  and  are  therefore  not  plentiful 
enough  to  do  much  harm.  But,  as  it  never  can  be  cer- 
tainly told  when  a  water  so  contaminated  becomes  safe  for 

1  According  to  the  report  of  the  Rivers  Pollution  Commission  some 
years  ago,  no  stream  in  England  is  of  sufficient  length  to  purify  itself 
satisfactorily  of  the  sewage  contamination  it  is  liable  to  receive.  On 
the  other  hand,  according  to  a  report  (April,  1903)  of  the  Commissioner 
of  Health  of  Chicago,  very  careful  and  extensive  investigation  shows  that 
the  large  quantity  of  sewage  from  that  city  discharged  into  the  Illinois 
River  has  entirely  disappeared  long  before  the  latter  empties  into  the 
Mississippi  at  a  point  over  250  miles  from  Chicago. 


SUBSOIL-  OK  GROUND-WATERS  157 

use  again,  and  as  the  population  of  most  towns  and  their 
consequent  sewage  production  are  constantly  increasing, 
while  the  quantity  of  water  in  the  receiving  streams 
remains  about  the  same  or  is  diminishing  from  year  to 
year,  the  use  of  such  water  should  be  avoided  if  possible; 
or,  if  it  must  be  used,  it  should  be  purified  and  made 
reasonably  safe  by  the  most  scientific  and  efficient  means 
and  methods  available. 

Water  from  large  fresh-water  lakes  will  be  of  the  best 
quality,  provided  it  be  taken  from  a  point  sufficiently 
distant  from  the  shore  to  escape  all  danger  of  sewage 
contamination.  Chicago  apparently  lowered  the  mortality 
percentage  from  typhoid  fever  from  7.2  in  1891  to  an 
average  of  2.1  for  the  decade  1896-1905,  and  to  1.1  for 
1908,  by  preventing  as  far  as  possible  the  discharge  of 
sewage  into  Lake  Michigan  and  by  taking  the  water- 
.  supply  from  the  lake  at  a  minimum  distance  of  two  miles 
instead  of  1400  feet  from  shore  as  formerly.^  Water  from 
small  lakes  or  ponds,  and  even  from  storage  reservoirs,  may 
become  offensive  to  taste  and  smell  through  the  growth  in 
them  of  minute  vegetable  organisms,  such  as  the  algae, 
though  it  is  not  known  that  these  are  prejudicial  to  health. 

Subsoil-  or  Ground-waters. — Ordinarily,  water  loses 
much  organic  matter  as  it  percolates  through  the  soil,  but 
takes  up  considerable  carbon  dioxide  from  the  soil-air, 
which  increases  its  solvent  powers  so  that  it  may  also 
dissolve  some  of  the  mineral  constituents  of  the  soil 
through  which  it  passes.  When  these  mineral  substances 
become  so  great  in  amount  as  to  give  the  water  a  decided 
taste  or  medicinal  properties,  we  call  it  a  mineral  water; 
but  when  the  inorganic  matter  does  not  render  it  ob- 
jectionable to  the  taste  or  too  hard,  the  water,  whether 
subsoil  or  artesian,  will  usually  be  quite  safe  and  usable 
in  so  far  as  the  mineral  matters  are  concerned. 

Attention  has  already  been  called  to  the  pollution  of 

1  One  water-supply  extends  only  3300  feet  out  into  the  lake,  but  this 
supplies  not  more  than  12,500  persons  in  the  extreme  north  end  of  the 
city,  and  the  water  is  sand-filtered. 


158        -  WATER 

the  soil.  How,  then,  can  the  water  in  passing  through  it 
lose  its  organic  contents  and  become  pure?  Partly  by 
mechanical  filtration,  but  mainly  through  the  combined 
action  of  the  saprophytic  soil-bacteria  and  the  oxygen  of 
the  soil-air,  which  rapidly  convert  the  organic  impurities, 
both  suspended  and  dissolved,  into  simpler  and  harmless 
end-products.  The  substances  of  vegetable  nature  are 
ultimately  resolved  by  these  agencies  into  carbon  dioxide, 
water,  etc.,  while  those  of  animal  origin  and  containing 
nitrogen  give  rise  to  the  various  ammonia  compounds,  or 
may  be  further  oxidized  into  nitrous  and  nitric  acids  and 
their  salts,  all  entirely  harmless  in  the  proportions  in 
which  they  are  found  in  the  percolating  ground-water. 


River 

Flood  plain 


Fig.   40. — Section  showing  relation  of  water   table  to   surface  irregu- 
larities.    (U.  S.  Geological  Survey,  Water-supply  Paper  255.) 

but  all  of  great  value  as  nutrients  for  the  higher  plant- 
life  of  the  soil. 

The  rate  of  percolation  has  much  to  do  with  the  com- 
pleteness and  perfection  of  this  action,  for  ample  time 

,^  must  be  had  for  the  organic  decompositions  to  occur. 
Therefore,  anything  that  retards  the  downward  flow  of 
water  favors  its  purification,  and  anything  that  increases 

^  its  movement  decidedly  affects  for  the  worse  its  ultimate 
quality  and  character. 

The  importance  of  this  biological  soil  action  can  scarcely 
be  overestimated,  and  the  student  should  endeavor  to 
appreciate  not  only  the  bearing  which  it  has  in  the  great 
scheme  of  nature's  adaptation  of  means  to  ends,  but  also 


FLOW  OF  SUBSOIL-WATER 


159 


the  importance  of  our  utilization  of  it  in  the  artificial 
purification  of  our  environment  and  in  the  disposal  of 
waste  matters.  We  must  understand,  however,  that  for 
every  soil  only  a  definite  amount  of  work  can  be  ac- 
complished by  the  agencies  mentioned  and  under  the 


Fig.  41. — Diagram  showing  how  wells  and  springs  may  be  affected 
by  geologic  conditions,  surface  elevation  and  by  differences  in  location 
and  depth.  A,  limestone  showing  both  small  and  large  passageways; 
B,  jointed  crystalline  rock;  C,  solid  crystalline  rock;  D,  alluvial  soil; 
E,  comparatively  impervious  stratum,  as  clay;  F,  stratum  composed 
of  sand,  gravel,  bowlders,  clay  and  mixtures  of  them;  G,  comparatively 
impervious  stratum,  as  clay  or  hardpan;  H,  porous  sandstone;  J,  fissure 
spring  (may  be  contaminated  easily  by  campers  or  others) ;  K,  water 
table  or  line  below  which  ground  is  saturated;  L,  flowing  well  (strikes 
joints  carrying  water) ;  M,  non-flowing  well  (strikes  no  joints) ;  A^, 
shallow  well  (strikes  a  pocket  of  sand) ;  O,  seepage  spring  (yield  small 
and  perhaps  during  wet  weather  only);  P,  shallow  and  poor  well;  Q, 
artesian  well  (strong  flow);  R,  artesian  well  (bottom  in  sand,  flow  mod- 
erate) ;  »S,  T,  non-flowing  artesian  wells  (head  insufficient  to  force  water 
to  the  surface  of  the  high  ground) ;  U,  well  in  clay  (no  yield) ;  V,  shallow 
well  in  sand ;  W,  hillside  spring  (both  V  and  W  are  liable  to  contami- 
nation from  the  house  wastes  above) ;  X,  shallow  and  dry  well  (bottom 
in  clay  and  against  a  bowlder) ;  Y,  flowing  well  (bottom  in  sand) ;  Z, 
dry  well  (same  depth  as  well  Y  but  sunk  where  the  water-bearing  bed 
thins  out).  (Water  Systems  for  Farm  Homes,  U.  S.  Department  of 
Agriculture,  Farmers'  Bulletin,  p.  941.) 


conditions  existing  at  any  given  time.  In  other  words, 
there  is  here  also  a  limit  of  permissible  impurity,  and  if 
this  limit  is  exceeded,  the  conditions  become  unnatural, 
the  bacterial  and  chemical  action  is  inadequate,  and  the 
descending  water  is  not  thoroughly  purified  as  it  perco- 
lates through  the  overcharged  soil. 


160 


WATER 


The  subsoil-water  slowly  sinks  through  the  ground  until 
at  some  level  or  other  it  reaches  an  impermeable  stratum, 
where  it  is  retained  in  natural  basins  or  escapes  at  some 
outcropping  of  the  stratum  below  the  water-level,  thus 
forming  a  spring.  (Figs.  39,  40,  and  42).  The  level  of 
the  water  in  these  undergound  reservoirs  is  constantly 
changing  according  to  the  season,  rainfall,  discharge  from 
springs,  etc.,  though  ordinarily  the  variation  for  any  given 
place  differs  little  from  year  to  year.  It  is  from  wells 
sunk  to  these  water-bearing  strata  and  from  springs  that 
water  is  obtained  for  the  majority  of  people  who  do  not  live 
in  towns  or  cities  supplied  by  water-works  (Fig.  40).  These 


Fig.  42. — Representing  the  difference  between  shallow  and  deep  wells, 
and  between  the  high-water  and  low-water  level  of  the  ground-water: 
a,  soil  and  gravel ;  b,  clay  or  rock ;  c,  c,  high-water,  and  d,  d,  low-water 
level. 


underground  bodies  of  water  are  in  constant  motion  toward 
one  or  more  outlets  at  more  or  less  distant  points,  but  the 
currents  are  usually  quite  sluggish  owing  to  the  friction 
and  capillary  force  of  the  particles  of  soil  through  which 
they  pass.  For  the  same  reasons  the  surface  of  the  water 
is  not  horizontal  but  curved,  the  curve  being  sharpest 
near  the  outlet,  and  the  difference  in  level  between  high 
and  low  water  is  least  near  the  outlet;  also,  the  higher 
the  level  the  greater  the  fall  to  the  outlet  and  the  greater 
the  discharge.     (Fig.  42.) 

The  outflow  from  most  continuously  flowing  springs 
represents  the  percolation  through  and  drainage  of  such 


CONTAMINATION  OF  SUBSOIL-WATER 


161 


a  comparatively  large  area  that  it  is  not  probable  that 
any  considerable  proportion  of  this  area  will  be  exces- 
sively polluted,  nor  that  the  percolate  from  any  and 
all  overpolluted  parts  of  it  will  be  so  concentrated  and 
charged  with  harmful  impurities  that  the  thoroughly  puri- 
fied water  from  the  remainder  of  the  area  will  not  be 
sufficient  to  dilute  it  sufficiently  to  eliminate  all  danger 
to  health  from  its  use.     Consequently,  springs  are  to  be 


Fig.  43. — Map  showing  position  of  water-table  by  contours  (contin- 
uous lines),  lines  of  motion  of  ground- water  (arrows),  and  surface- 
streams.      (U.  S.  Geological  Survey,  Water-supply  Paper  255.) 

ranked  among  the  best   and    safest  sources  of  natural 
waters,  and  general  experience  sustains  the  judgment. 

But  the  remarks  regarding  the  purity  of  spring-water 
do  not  hold  good  for  water  from  ordinary  shallow  wells — 
provided  they  do  not  pass  through  an  impermeable 
stratum — or  from  springs  where  the  water  passes  almost 
directly  from  surface  to  outlet,  for  in  both  cases  the 
filtering  action  of  the  soil  and  the  removal  of  organic 
11 


162  WATER 

matter  by  the  prolonged  action  of  the  saprophytic  bacteria 
are  Ukely  to  be  incomplete  and  imperfect.  Likewise, 
water  from  springs  that  drain  a  limited  and  extensively 
polluted  area  may  be  seriously  contaminated,  and  unsafe 
to  use. 

Especially  about  human  dwellings,  where  wells  are  com- 
monly located  for  the  sake  of  convenience,  are  filth  and 
pollution  likely  to  be  carried  into  the  water,  for  sewage 
and  dirt  of  almost  every  kind  accumulate  in  constantly 
increasing  quantity  in  the  soil  about  a  house,  and  always 
tend  to  exceed  the  limit  of  permissible  impurity.  There  is 
also  the  ever-present  danger  of  the  water  receiving  the 
specific  germs  of  disease  from  the  human  wastes  of  the 
household,  no  matter  in  what  condition  the  surrounding 
soil  may  be.  In  this  connection  it  is  well  to  call  attention 
to  the  fact  that  the  visit  of  a  transient  and  possibly 
unsuspected  typhoid-  or  other  "carrier"  to  a  house  or 
locality  may  be  the  source  of  an  infection  through  the 
well-water  and  thus  serve  to  explain  the  occurrence  of  a 
given  disease  where  it  has  not  occurred  for  a  long  time 
previously,  if  ever. 

Owing  to  the  lessening  of  lateral  resistance  the  surface- 
water  passes  rapidly  and  almost  directly  into  the  well 
(unless  the  wall  of  the  latter  be  made  water-tight  to 
almost  the  full  depth),  and  may  carry  with  it  solutions  of 
all  the  impurities  polluting  the  soil  about  the  mouth ;  and 
as  wells  drain  a  very  considerable  area — Parkes  says  one, 
in  ordinary  soils,  whose  radius  is  equal  to  four  times  the 
depth  of  the  well — there  are  few  wells  about  which  such 
an  area  is  not  subject  to  dangerous  pollution.  (Fig.  44.) 
Moreover,  the  influence  of  pumping  or  other  sudden  with- 
drawal of  water  from  the  well  is  even  more  important, 
since  it  extends  a  distance  from  15  to  150  times  the  tem- 
porary depression  of  the  water-level,  and  impurities  may 
thus  be  drawn  into  the  well  which  ordinarily  would  tend 
to  flow  away  from  it.    (Fig.  45.) 

Excepting  the  bacteria,  which  pass  freely  through 
almost  all  soils  when  resistance  to  the  water-current  is 


DEEP  WATERS 


163 


markedly  diminished,  only  such  portions  of  the  pollution 
as  can  be  dissolved  may  reach  the  water  in  the  well;  and 
it  is  a  fact  that  many  waters  thus  polluted  are  sparkling 
and  clear,  with  a  pleasant  taste  and  no  bad  odor,  so  that 
any  suspicion  as  to  their  real  character  may  be  wanting. 
Moreover,  even  though  specific  disease  germs  be  absent, 
there  is  always  danger  that  the  contamination  may 
become  so  concentrated  as  to  produce  serious  results,  and 
this  may  occur  in  various  ways:  (a)  the  well  may  be  so 
deep  or  the  character  of  the  soil  such  that  in  ordinary 
weather  the  liquid  passing  through  the  soil  is  so  purified 


Fig.  44. — Representing  the  difference  of  percolation  about  cased  (d)  and 
uncased  (e)  wells:   a,  soil  and  gravel;   b,  clay  or  rock;   c,  cesspool. 


that  it  imparts  no  harmful  properties  to  the  water;  but  if 
the  soil  is  being  continually  infiltrated  with  dangerous 
impurities  and  if,  at  length,  heavy  rains  or  continued  wet 
weather  supervene,  there  may  be  more  and  more  of  these 
impurities  dissolved  and  carried  into  the  well  until  the 
proportion  of  harmful  matter  in  the  water  passes  the 
safety-line,  and  as  a  result  there  is  marked  illness  or 
increased  predisposition  to  disease  among  those  using  the 
water;  or  (6)  in  continued  dry  weather  the  ground-water 
may  be  lessened  to  such  an  extent  that  the  impurities  that 
were  formerly  well  diluted  become  sufficiently  concen- 


164 


WATER 


trated  to  cause  sickness,  even  though  there  be  no  unusual 
pollution  of  the  soil  about  the  well;  or  (c)  the  water-level 
in  the  well  being  suddenly  or  persistently  lowered,  a 
greater  area  is  drained  and  additional  collections  of 
sewage  may  flow  into  the  well.     (Fig.  44.) 

Deep  Waters. — Deep  wells  are  those  which  pass  through 
an  impermeable  stratum,  and  so  do  not  get  their  supply 
from  the  subsoil-water.  The  relative  depth  of  two  wells 
is  no  exact  criterion  as  to  their  classification,  as  the  shal- 
lower one  may  really  be  a  "deep"  one  and  the  deeper  a 
"shallow"  one,  according  to  the  presence  or  absence  of 


Fig.  45. — Showing  depression  of  water  in  shallow  well  caused  by 
pumping:  A,  well;  B,  cesspool;  C,  underground  water-curve.  (After 
Field  and  Peggs.) 


the  impermeable  stratum.     Artesian  wells  are  very  deep 
wells,  piercing  one  or  more  impermeable  strata. 

Sometimes  the  water  rises  and  flows  out  of  the  mouth 
of  a  deep  well,  in  which  case  the  supply  is  drawn  from  a 
water-bearing  stratum  between  two  impermeable  ones,  and 
which  has  its  only  outcroppings  higher  than  the  top  of  the 
well.  (Fig.  46.)  The  water  accumulates  in  this  natural 
reservoir  above  the  level  of  the  well-mouth,  and  is  forced 
out  when  an  opening  is  made  through  the  uppermost 
impermeable  stratum.  Deep  well-water  is  apt  to  be  of 
much  better  quality  than  that  frona  shallow  wells,  since  it 


PURITY  OF  DEEP  WELL-WATER 


165 


usually  represents  the  total  percolation  from  a  very  large 
extent  of  ground  surface,  within  the  limits  of  which  the 
combined  areas  and  amount  of  pollution  are  insignificant 
in  comparison,  any  possible  impurities  in  the  water  being 
consequently  reduced  by  dilution  to  much  below  the 
danger-point.  It  is  for  the  same  reason  that  there  is  such 
a  difference  in  the  quality  of  spring-water  and  of  that 
from  most  shallow  wells.  Though  the  two  waters  seem  to 
have  a  common  source,  one  is  the  composite  water  of  a 
large  district,  in  which  the  average  impurity  or  con- 
tamination per  unit  of  surface  may  be  infinitesimal;  the 
other  is  mainly  the  special  percolate  from  a  limited  area, 
which  is,  for  the  reasons  given,  particularly  liable  to  be 
highly  and  dangerously  polluted.^ 


Fig.  46. — Representing  the  spontaneous  flow  of  deep  or  artesian  wells, 
B  and  C:  a,  a,  water-level  in  deep  pervious  strata,  F,  F;  A,  intermittent 
spring  at  out-cropping  of  F,  F  above  impermeable  stratum,  E,  E;  D, 
shallow  well  in  upper  pervious  strata.     (Wilson.) 

It  is  also  to  be  remembered  that  in  many  of  the  strata  or 
beds  supplying  deep  or  artesian  wells  the  water  has  been 
collecting  for  a  very  long  time,  possibly  even  for  centuries, 
and  it  is  incredible  that  organic  pollution  should  persist 
with  power  for  harm  through  periods  of  such  duration. 

Artesian  or  deep  well-water  will  also  likely  be  very  free 
from  organic  matters,  but  possibly  heavily  charged  with 

'  Of  course,  the  water  in  shallow  wells,  as  in  others,  is  being  continu- 
ally changed  by  the  onward  movement  of  the  underground  current;  but 
where  this  is  slow  in  comparison  with  the  percolation  from  the  surface, 
the  impurities  of  the  latter  will  be  in  excess  in  the  well-water. 


166 


WATER 


mineral  salts.  Should  these  latter  not  be  present,  the 
water  will  probably  be  of  excellent  quality;  though  if  the 
well  be  very  deep,  it  may  be  too  warm  for  immediate  use 
as  a  potable  water. 

Frequently  well-water,  and  that  most  often  from  shallow 
wells,  is  the  only  kind  available,  especially  in  country 
districts.  In  such  cases  care  must  be  taken  that  impurities 
are  kept  out  of  the  well  by  all  possible  means.  If  this  be 
done,  water  may  often  be  had  of  excellent  quality.  The 
area  about  all  wells  should  be  kept  clean,  and  the  well 
should  be  as  distant  as  possible  from  any  source  of  con- 
tamination, especially  if  the  latter  be  a  constant  one. 
Wells  should  be  walled  or  cased,  shallow  wells  to  below 


Fig.  47. 


-Diagram  showing  ordinary  location  of  farm  well.     (U.  S. 
Geological  Survey,  Water-supply  Paper  255.) 


the  water-level  and  deep  wells  to  the  first  impermeable 
stratum,  if  possible,  in  order  to  cause  the  water  to  percolate 
through  as  much  soil  as  possible  before  entering  the 
well,  in  this  way  checking  the  rapidity  of  its  descent  and 
prolonging  the  biological  action  of  the  top-soil.^     Wells 

1  As  the  saprophytic  and  nitrifying  bacteria  are  only  found  normally 
in  the  first  few  feet  of  top-soil,  where  the  conditions  are  favorable  to 
their  existence  and  growth,  we  cannot  expect  to  have  any  further  action 
by  them  after  the  water  reaches  its  underground  level  and  begins  to 
move  toward  its  outlets.  Nor  will  there  be  any  filtration  in  this  on- 
ward progress,  for  that  has  been  accomplished  in  the  upper  layers.  It 
is  for  this  reason  that  the  filtrate  from  cesspools  and  similar  pits  is  not 
organically  purified,  but  is  especially  obnoxious  and  dangerous  as  it 
traverses  the  soil,  for  the  bottoms  of  such  pits  are  usually  below  the 
biological  level,  and  there  is  also  in  them  a  lack  of  the  oxygen  necessary 
to  maintain  the  action  of  the  nitrifying  bacteria. 


TESTING  OF  WELL-WATER 


167 


should  also  have  a  properly  constructed  covering  and  curb, 
to  keep  out  splashings  and  drippings  of  muddy  or  dirty 
water.     (Fig.  48.) 

In  this  connection  Sedgwick  says:  "Excepting  those 
cases  in  which  cracks  or  fissures  in  the  earth  allow  direct 
communication  between  polluting  sources  and  wells  of 
drinking-water,  the  author  is  strongly  of  the  opinion  that 
in  most  cases  in  which  infection  exists  in  wells,  the  pollut- 
ing material  has  found  its  way  in  from  the  top."  "When 
one  reflects  on  the  carelessness  with  which  wells  used  as 
sources  of  drinking-water  are  exposed  to  the  access  of  filth 
from  the  top,  such  wells  often  being  only  loosely  covered 
by  planks,  it  is  easy  to  see  that  from  the  boots  of  work- 


FiG.  48. — Well  protection.  (Bulletin  57  of  the  U.  S.  Dept.  of  Agriculture.) 

men,  or  from  children  playing  on  the  planks,  or  from 
poultry  walking  about  and  carrying  infection  on  their 
feet,  pollution  may  take  place.  "^ 

We  must  not  forget  that  wells  drain  a  large  area.  As 
the  ground-water  has  a  constant  movement  in  the  direc- 
tion of  natural  outlets,  the  well  should  be  so  located  that 
the  current  flows  from  it  toward  any  near-by  cesspool  or 
other  source  of  pollution.  (Fig.  47.)  The  direction  of  the 
underground  current  can  generally  be  determined  by  not- 
ing the  location  of  the  nearest  spring  or  water-course,  by 


Principles  of  Sanitary  Science  and  the  Public  Health,  1902,  p.  351. 


168 


WATER 


observing  the  dip  of  the  underlying  strata,  or  by  digging 
holes  at  equal  distances  about  the  well  and  dissolving  salt 
or  an  aniline  dye  in  them  in  turn,  and  testing  the  water 
from  the  well  after  a  time  for  the  salt  or  color.  If  a 
well  be  much  deeper  than  a  neighboring  cesspool,  it  may 
drain  from  the  latter,  even  in  opposition  to  the  ground- 
water current,  especially  if  the  water  in  the  well  be  sud- 
denly lowered.  Again,  dangerous  impurities  have  been 
carried  into  wells  from  long  distances  through  fissures  or 


Fig.  49. — Diagram  showing  danger  of  pollution  where  casing  is  carried 
only  to  rock.     (U.  S.  Geological  Survey,  Water-supply  Paper  255.) 

crevices  in  rock.  Harrington  cites  the  case  of  a  well  which, 
"bored  500  feet  into  red  sandstone,  drained,  through  fis- 
sures, all  the  shallow  wells  in  the  vicinity.  These  being 
of  no  use  as  wells,  were  then  utilized  as  cesspools,  and 
draining  again  through  the  fissures,  caused  the  well  to 
become  so  foul  that  it  had  to  be  abandoned."  (Figs.  49 
and  50.) 

The  water  from  the  well  should  be  frequently  tested  for 
chlorides  and  nitrates,  these  usually  indicating  sewage  con- 
tamination, and  this  should  be  done  especially  after  heavy 


WATER-SUPPLY  AND  TYPHOID  FEVER 


169 


rains  and  also  when  the  water  in  the  well  becomes  low.  The 
taste  and  odor  of  the  water  should  also  be  noted  after 
standing  for  a  time  or  on  being  heated.  Some  other 
sources  should  be  sought  whenever  such  tests  show  con- 
tamination or  when  there  are  cases  of  infectious  disease 
near  at  hand.  Boiling  the  water  and  filtration  are  always 
to  be  recommended  whenever  there  is  the  least  suspicion 
as  to  impurity  or  infection. 


Fig.  50, — Pollution  of  subsurface-water  in  limestone.     (Bulletin  57  of 
the  U.  S.  Dept.  of  Agriculture. 


Shallow  or  subsoil  wells  in  thickly  settled  towns  should 
not  be  used  to  supply  drinking-water  or  cooking-water, 
as  the  soil  is  always  more  or  less  saturated  with  filth  and 
sewage,  and  it  is  practically  impossible  in  such  places  to 
locate  a  well  w^hich  will  not  be  in  constant  danger  of 
receiving  harmful  impurities  from  some  source  or  another. 

In  an  investigation^  made  by  the  author  in  1904 
he  discovered  that  the  incidence  of  typhoid  fever  is 
greater  in  districts  essentially  rural,  and  not  in  those 
which  include  the  great  cities,  many  of  which  latter  are 
known  to  have  had  high  death-rates  from  this  disease, 
and  all  of  which  have  water-supplies  which  may,  if  not 
properly  cared  for,  serve  as  common  carriers  of  infection  to 
their  enormous  populations.  As  the  data  from  which  this 
study  was  made  were  taken  from  the  Report  on  Vital 

*  Typhoid  Fever  in  Relation  to  the  Urban  and  Rural  Population  of 
the  United  States,  American  Medicine,  April  22,  1905,  pp.  649-652. 


170  WATER 

Statistics  of  the  U.  S.  Census  of  1900,  it  must  be  remem- 
bered that  all  cities  and  towns  of  less  than  8000  popula- 
tion were  classified  with,  and  that  they  collectively  made 
up  a  large,  if  not  the  greater  part  of  the  so-called  rural 
population.  Now,  in  the  smaller  towns  and  villages  it  is 
more  than  probable  that  the  inhabitants  are  supplied 
from  private  and  shallow  wells  and  cisterns,  rather  than 
from  common  sources,  such  as  reservoirs,  springs,  arte- 
sian wells  or  modern  filter  plants,  and,  consequently,  there 
is  continual  danger  in  such  communities  of  the  water 
being  contaminated  by  neighboring  cesspools  and  other 
sources  of  pollution,  this  danger  rapidly  increasing  as  the 
villages  grow  in  size,  for  these  wells  and  cesspools  are 
brought  closer  together,  and  the  entire  body  of  ground- 
water supplying  the  wells  is  correspondingly  more  liable 
to  be  polluted  beyond  the  limit  of  safety  or  to  become  at 
any  time  the  common  carrier  of  infection.  Hence  it  is 
easy  to  understand  how  the  so-called  rural  populations 
actually  have,  as  a  rule,  a  relatively  higher  sick-  and 
death-rate  from  typhoid  fever  than  do  the  dwellers  in 
large  cities;  and  it  should  be  equally  evident  that  it  will 
be  the  part  of  wisdom  for  small  communities  to  employ 
every  possible  means  to  secure  improved  and  non-polluted 
water-supplies  for  the  common  use  of  their  respective 
populations. 

The  decision  as  to  the  quality  of  any  water  must  in  each 
case  be  determined  by  all  the  circumstances  available 
which  relate  to  it,  and  these  should  all  be  thoroughly  in- 
vestigated before  rendering  an  opinion,  as  some  of  them 
may  counteract  the  others.  However,  other  things  being 
equal,  the  value  of  a  water  will  probably  be  in  accord 
with  the  following  table: 

1.  Spring-water,  1   Very 

Wholesome  ■    2.  Deep  well-water,  /       palatable 

3.  Water  from  unpolluted  streams,         \  Moderately 
Q       .  .  f  4.  Stored  rain-water,  /       palatable, 

buspicious     <    g_  Surface-water  from  cultivated  land. 


j^  f  6.  Sewage-polluted  river-water, 

\  7.  Shallow  well-water. 


Palatable. 


CLASSIFICATION  OF  WATERS 


171 


Fig.  ol. — Showing  death-rates  from  typhoid  fever  in  1894  in  sixty-six 
cities,  grouped  according  to  the  quality  of  their  drinking-water.  (Re- 
produced with  the  permission  of  the  author,  Mr.  James  H.  Fuertes,  and 
of  the  Association  of  Civil  Engineers  of  Cornell  University.) 


172  WATER 

We  may  also  classify  waters  as  follows:  (1)  Pure  and 
wholesome  water;  (2)  usable  water;  (3)  suspicious  water; 
(4)  dangerous  water.  (See  chart  on  page  171  and  table 
on  page  228.)  Pure  waters  and  usable  waters  may  be  used 
without  filtration;  those  of  the  third  class  should  be  fil- 
tered before  distribution,  and  also  at  the  house  before  use, 
if  possible,  and  a  purer  source  sought  or  all  sewage- 
pollution  prevented.  Those  of  the  fourth  class  should 
not  be  used  at  all  except  when  absolutely  unavoidable, 
and  then  only  after  purification  by  all  the  means  at 
command. 

Inasmuch  as  most  large  cities  must  from  necessity  fur- 
nish a  water  of  the  second  or  third,  and  occasionally  even 
of  the  fourth  class,  such  water  should  be  purified  as  much 
as  possible  before  distribution  by  storage  for  a  time  in 
settling  reservoirs  and  by  some  effective  system  of  filtra- 
tion, combining  these  with  chemical  treatment  if  necessary. 
As  much  of  the  organic  matter  is  oxidized,  and  many  of 
the  pathogenic  bacteria  are  destroyed  by  saprophytes  and 
other  causes  while  the  water  is  standing  in  the  settling 
reservoirs,  and  as  properly  constructed  and  well-managed 
filters  are  even  more  efficacious  to  this  end,  a  water  origin- 
ally suspicious  or  worse  may  often  be  made  usable  by  the 
above  means  properly  employed.  Not  only  must  the 
storage  reservoirs  and  filtering  apparatus  be  kept  clean 
and  in  good  working  order,  but  care  must  also  be  had 
that  the  distributing  apparatus  does  not  permit  soil-air 
or  sewer-gas  or  sewage  to  be  drawn  in  through  leaks  in  the 
mains  at  times  when  the  flow  is  intermittent,  and  that 
lead  pipes  are  not  used  for  conveying  drinking-water  if 
the  character  of  the  water  is  such  that  it  acts  on  that 
metal. 

A  good  potable  water  should  be  perfectly  clear,  free 
from  odor  or  taste,  cool,  well  aerated  and,  if  possible,  soft 
or  with  only  a  mild  degree  of  hardness.  Circumstances 
must  determine  the  amount  of  dissolved  matters  permis- 
sible; what  is  an  excess  in  one  case  might  not  be  so  in 
another. 


DISEASES  DUE  TO  IMPURE  WATER  173 

DISEASES  CAUSED  BY  IMPURE  DRINKING  WATER. 

A  polluted  water  may  carry  the  organisms  of  infectious 
diseases,  or  it  may  cause  or  favor  the  development  of  dis- 
eases which  are  not  due  to  specific  germs.  In  addition  to 
these,  and  of  at  least  equal  importance  from  a  sanitary 
point  of  view,  is  the  depressed  state  of  the  system  that 
the  habitual  use  of  impure  drinking-water  causes,  and  the 
predisposition  to  disease  that  ensues.  By  the  faculty  of 
accommodation  and  through  long  habit  a  community  may 
become  so  protected  against  an  impure  water  as  to  mani- 
fest no  striking  symptoms,  while  strangers  may  be  seri- 
ously affected  by  it;  but  even  in  such  a  case  the  condition 
of  those  habitually  using  the  water  will  probably  be  more 
or  less  depressed  and  not  that  of  perfect  health. 

The  non-infectious  diseases  likely  to  be  caused  by  im- 
purities in  the  drinking-water  are  primarily  those  affecting 
the  alimentary  tract,  as  dyspepsias,  diarrheas,  and  other 
disturbances  having  their  origin  in  severe  or  chronic 
gastric  or  intestinal  irritation.  So,  also,  impure  water, 
even  though  it  does  not  contain  the  actual  germs,  may 
have  much  to  do  in  bringing  on  an  attack  of  typhoid 
fever,  specific  dysentery  or  other  infectious  disease  by  so 
lowering  the  resistance  of  the  body  as  to  make  it  espe- 
cially receptive  to  the  cause  of  the  malady  when  introduced 
from  another  source. 

Large  quantities  of  the  sulphates  of  calcium  and  mag- 
nesium are  thought  to  have  special  influence  in  causing 
dyspepsias,  with  loss  of  appetite,  pain  at  the  epigastrium, 
etc.  An  excess  of  iron  in  water  is  also  prone  to  produce  con- 
stipation, headache,  loss  of  appetite  and  malaise.  Goitre 
and  the  formation  of  vesical  calculi  are  each  supposed 
to  be  due  to  mineral  or  inorganic  impurities,  although 
the  true  relation  of  impure  drinking-water  to  these  dis- 
eases is  still  unsettled.  "It  has  long  been  a  popular 
opinion  that  drinking  lime-waters  gives  rise  to  calculi  of 
the  oxalate  and  phosphate  of  calcium,"  and  the  "opinion 
that  impure  water  is  the  cause  of  goitre  is  as  old  as  Hip- 


174  WATER 

pocrates  and  Aristotle.''  Further  study  of  the  principles 
underlying  the  treatment  of  goitre  with  glandular  extracts 
may  make  it  easier  to  determine  whether  impure  water 
has  a  causative  influence  in  the  production  of  this  disease. 

Diarrhea  may  be  caused  by  any  of  the  following  im- 
purities in  water:  suspended  substances  of  any  kind,  but 
especially  those  of  fecal  origin;  dissolved  animal,  vege- 
table, or  mineral  matters,  and  fetid  gases.  The  diarrhea 
produced  by  any  of  these  contaminants  may  be  so  severe 
as  to  simulate  true  dysentery  and  cause  doubt  as  to  the 
diagnosis. 

Certain  metals  may  be  taken  up  from  the  earth's  strata, 
or  from  the  lining  of  cisterns,  pipes,  etc.,  and  may  produce 
their  characteristic  toxic  symptoms  in  the  system.  Lead 
is  one  of  these  metals,  and  it  will  be  well  to  note  here  the 
waters  that  are  especially  apt  to  take  up  this  metal.  Pure 
waters  and  those  containing  much  oxygen  act  powerfully 
on  lead,  as  do  those  containing  organic  nitrates  and  nitrites, 
especially  ammonium  nitrate.  Waters  containing  carbon 
dioxide  and  the  salts  of  calcium  and  magnesium  and  those 
free  from  absorbed  gases  act  least  on  lead,  and  carbon 
dioxide  seems  even  to  protect  lead  by  forming  an  insolu- 
ble carbonate  on  leaden  surfaces,  but  water  containing  car- 
bon dioxide  may  take  up  lead  for  a  time  from  new  pipes 
until  the  insoluble  carbonate  is  deposited  within  them.  It 
has  also  been  shown  that  in  some  cases  wherein  cold  water 
does  not  act  upon  the  metal  hot  water  will  dissolve  a  small 
but  appreciable  quantity  of  it.  Copper,  zinc,  and  arsenic 
are  also  metals  that  may  be  taken  up  by  certain  waters, 
and  that  may  cause  serious  results  from  the  use  of  the 
latter.  Lead  is  more  easily  dissolved  if  other  metals  are 
in  contact  with  it,  probably  owing  to  electrolytic  action. 
Lead  should  not  be  used  for  pipes  nor  to  line  cisterns 
unless  suitable  tests  show  that  the  water  does  not  affect 
it,  nor  should  any  water  be  used  in  which  the  tests  show 
more  than  one-thirtieth  of  a  grain  of  lead  per  gallon. 

Of  the  infectious  diseases,  germs  of  typhoid  fever, 
cholera,  and  dysentery  are  usually  carried  into  the  system 


TRANSMISSION  OF  INFECTION  BY  WATER     175 

by  the  drinking-water,  while  the  same  is  sometimes  true  of 
scarlet  fever,  diphtheria,  and  kindred  diseases. 

For  a  long  time  the  belief  that  malaria  is  very  frequently, 
if  not  most  often,  transmitted  by  the  drinking-water,  was 
held  by  many  sanitarians,  and  there  has  seemed  to  be 
much  circumstantial  evidence  to  substantiate  this  opinion. 
However,  careful  scientific  investigation  has  proved  that 
this  disease  can  be,  and  usually  is,  due  to  direct  inoculation 
by  at  least  one  species  of  mosquito,  which  acts  as  an 
intermediary  host  in  the  life-cycle  or  development  of  the 
malarial  organism  (Plasmodium  H^Jalariae),  and  almost  all 
authorities  believe  that  the  disease  is  only  transmitted 
in  this  way. 

But,  as  with  the  impurities  causing  non-infectious  dis- 
turbances, water  containing  disease  germs  may  some- 
times be  used  for  a  long  time  by  those  accustomed  to 
it  without  the  development  of  the  specific  malady,  and  it 
may  only  be  after  the  system  is  weakened  by  excesses  or 
other  predisposing  conditions  that  the  disease  manifests 
itself;  or  it  may  happen  that  only  strangers  and  non- 
immunized  inhabitants  incur  the  disease.  It  has  been 
suggested  that  this  immunity  is  probably  brought  about 
by  the  very  gradual  introduction  into  the  body  of  the  dis- 
ease germs  and  their  poisons,  so  that  residents  of  the 
locality  are  not  susceptible  to  the  small  numbers  or  quan- 
tities of  these  which  are  sufficient  to  give  rise  to  the 
symptoms  of  the  particular  diseases  in  newcomers. 

It  is  sometimes  difficult  to  determine  just  when  or  how 
a  water-supply  has  been  infected  with  pathogenic  organ- 
isms, but  recently  it  has  been  shown  that  a  person  who 
has  recovered  from  a  transmissible  malady  may  continue 
to  carry  about  in  his  body  and  to  excrete  the  disease  germs 
for  a  long  time.  Thus  the  bacteria  of  typhoid  fever 
may  be  found  for  months  in  the  urinary  or  fecal  excre- 
tions of  a  considerable  proportion  of  those  who  have  had 
that  disease  and,  in  some,  for  even  years  thereafter;  many 
such  cases  having  been  reported  by  numerous  investi- 
gators.   It  is  therefore  easy  to  comprehend  how  such  a 


176 


WATER 


person,  going  from  place  to  place,  might  infect  not  one, 
but  many  sources  of  water-supply. 

The  following  table  gives  data  relating  to  some  notable 
epidemics  of  typhoid  fever: 


Location. 


Date. 


Lausen,  Switzerland 
Caterham,  England 
Plymouth,  Pa.     ' , 
Ithaca,  N.  Y. 
Butler,  Pa.       .      . 


1872 
1879 
1885 
1903 
1903-04 


Population. 

Cases. 

780 

144 

5,800 

352 

8,000 

1,104 

13,000 

1,300 

18,000 

1,348 

Deaths. 


21 
114 

78 
111 


Many  instances  have  been  recorded  which  practically 
prove  the  transmissibility  of  infectious  diseases  by  means 
of  drinking-water,  and  of  these,  reference  may  be  made 
to  the  epidemics  of  typhoid  fever  at  Lausen^  in  Switzer- 
land, at  Plymouth,  Pa.,^  Butler,  Pa.,  and  Ithaca,  N.  Y.; 
and  of  cholera  in  London.^  The  writer  himself  had  an 
opportunity  of  investigating  an  epidemic  of  typhoid  fever 
in  a  small  village  in  North  Carolina.^  In  this  there  were 
only  four  or  five  in  about  sixty  cases  which  were  not 
undoubtedly  due  to  contamination  of  the  subsoil-water  by 
the  infected  excreta  from  the  first  case;  and  of  four  of 
the  exceptions  (which  were  in  one  family),  the  first  was 
in  all  probability  infected  by  using  the  water  while  in 
attendance  upon  sick  neighbors,  and  the  others  by  direct 
contagion  from  the  first.  It  was  also  shown  that,  with 
the  exception  of  these  four,  the  cases  all  developed 
directly  along  the  lines  of  natural  drainage  leading  from 
the  residence  of  the  original  case — a  boy  who  came  to  the 
village  sick  with  the  disease— and  that  the  latest  cases  to 
develop  were  those  most  remote  from  the  starting-point 
of  the  infection. 

Moreover,  in  most  large  cities  of  this  and  other  countries 

1  Pepper's  System  of  Medicine,  vol.  i,  p.  250. 

2  Roh6's  Text-book  of  Hygiene,  2d  edition,  p.  63. 

3  Ibid.,  p.  64. 

*  University  Medical  Magazine,  May,  1892. 


PARASITIC  DISEASES  177 

the  typhoid  fever  death-rate  is  accepted  as  the  direct  index 
of  the  character  of  the  water-supply,  and  it  seems  to  be  a 
fact  almost  without  exception  that  any  marked  improve- 
ment in  the  latter  will  be  followed  by  an  immediate  and 
positive  reduction  in  the  former.  (See  chart  on  page  171.) 
The  same  may  also  be  said  to  hold  good  in  regard  to  diar- 
rheal diseases;  while  in  eastern  North  Carolina  there  has 
been  a  marked  reduction  in  the  prevalence  of  so-called 
malarial  fevers  —  which  are  probably  paratyphoid  in 
reality — as  a  result  of  the  efforts  of  the  State  Board  of 
Health,  to  persuade  the  people  to  substitute  rain-water 
or  deep  well-water  for  the  subsoil-water  which  was  almost 
universally  used  a  few  years  ago.^ 

The  ova  of  certain  parasites,  such  as  tape-worms  or 
round-worms,  may  often  be  taken  into  the  system  with 
the  drinking-water,  and  these  upon  developing  may  cause 
disturbances  that  may  require  more  than  the  slight  atten- 
tion usually  given  to  them.  Any  attack  of  convulsions 
in  a  child  or  other  severe  manifestation  of  reflex  action 
should  lead  to  the  inquiry  as  to  whether  these  parasites 
may  not  be  present,  and  whether  the  water-supply  has  not 
been  the  source  of  invasion. 

It  is  now  known  that  the  parasite  of  ankylostomiasis 
or  hook-worm  disease  may  also  be  carried  by  and  intro- 
duced into  the  human  body  by  the  drinking-water. 

Regarding  the  foregoing  remarks,  Parkes  makes  the 
following  statements:  "(1)  An  epidemic  of  diarrhea  in  a 
community  is  almost  always  owing  to  either  impure  air, 
impure  water,  or  bad  food.  If  it  affects  a  number  of 
persons  suddenly,  it  is  probably  owing  to  one  of  the  last 
two  causes,  and  if  it  extends  over  many  families,  almost 
certainly  to  water.  But  as  the  cause  of  the  impurity  may 
be  transient,  it  is  not  easy  to  find  experimental  proof. 
(2)  Diarrhea  or  dysentery  constantly  affecting  a  com- 

1  According  to  Hazen,  for  every  death  from  typhoid  fever  prevented 
by  the  purification  of  a  polluted  water-supply,  two  or  three  deaths  are 
prevented  from  other  causes.    This  statement,  Sedgwick  says,  he  has  been 
able  to  confirm  and  to  establish  as  conservative. 
12 


178  WATER 

munity,  or  returning  periodically  at  certain  times  of  the 
year,  is  far  more  likely  to  be  produced  by  bad  water  than 
by  any  other  cause.  (3)  A  very  sudden  and  localized 
outbreak  of  typhoid  fever  or  cholera  is  almost  certainly 
owing  to  the  introduction  of  the  poison  by  water.  (4)  The 
same  fact  holds  good  in  malarial  fevers,  and,  especially  if 
the  cases  are  very  grave,  a  possible  introduction  by  water 
should  be  inquired  into.  (5)  The  introduction  of  the  ova 
of  certain  entozoa  by  means  of  water  is  proved  in  some 
places,  probable  in  others.  (6)  Although  it  is  not  at  pres- 
ent possible  to  assign  to  every  impurity  in  water  its  exact 
share  in  the  production  of  disease,  or  to  prove  the  precise 
influence  on  public  health  of  water  which  is  not  extremely 
impure,  it  appears  certain  that  the  health  of  a  community 
always  improves  when  an  abundant  and  pure  water-supply 
is  given;  and,  apart  from  this  actual  evidence,  we  are 
entitled  to  conclude  from  other  considerations  that  abun- 
dant and  good  water  is  a  prime  sanitary  necessity."  The 
statistics  already  given  and  those  to  come  in  later  pages 
are  confirmatory  of  the  correctness  of  this  last  assertion, 
and  sanitary  authorities  now  realize  that,  in  addition  to 
the  mortality  from  typhoid  fever,  the  main  cause  of  an 
increase  in  the  death-rate  from  diarrheal  diseases  is  more 
often  to  be  fairly  attributed  to  a  contaminated  water- 
supply  than  to  improper  food  or  untoward  temperatures. 
Even  with  respect  to  cholera  infantum  (which  is  generally 
supposed  to  be  principally  due  to  the  influence  of  excessive 
heat  upon  the  infant  and  its  food)  a  number  of  epidemics 
show  a  closer  relation  to  impure  water-supply  than  to 
temperature-changes. 

THE  PURIFICATION  OF  WATER. 

Impurities  in  water  may  be  either  solid  matters  in 
suspension  or  dissolved  substances,  and  may  be  organic 
or  inorganic.  Any  turbidity  is  due  to  solid  particles, 
and  water  free  from  these  is  clear,  though  it  may  be 
colored  more  or  less  deeply  by  dissolved  matters.    But  a 


THE  PURIFICATION  OF  WATER  179 

clear  water  may  contain  such  solid  bodies  as  bacteria, 
animalculae,  ova  of  parasites,  etc.,  which  are  too  minute 
to  be  seen  with  the  naked  eye.  Whether  harmful  or  not, 
all  impurities  should  be  removed  in  so  far  as  it  is  possible 
from  all  supplies  of  drinking-water.  This  may  be  done  to 
a  considerable  extent  with  large  volumes  of  water  before 
distribution  to  consumers,  and  should  always  be  attended 
to  by  the  latter  if  the  water  is  not  already  clean  and 
within  the  limits  of  safety  when  they  receive  it.  In  fact, 
a  large  city  at  the  present  time  can  scarcely  have  a  more 
important  subject  for  consideration  than  that  of  obtaining 
and  supplying  the  purest  possible  water-supply  to  its  people. 
There  will  always  be  a  tendency  among  many  to  allow  matters 
to  continue  as  they  are  or  as  they  have  been  in  the  past, 
and  a  decided  objection  by  others  to  incurring  additional 
expense  for  what  may  seem  to  them  only  esthetic  reasons; 
but  no  matter  what  may  be  the  cost  of  providing  a 
reasonable  supply  of  pure  water  for  any  city's  personal 
and  domestic  uses,  a  very  little  consideration  will  show 
that  such  expenditure  is  true  economy  from  solely  a 
financial  point  of  view,  even  though  we  ignore  the  misery 
and  sorrow  of  the  sickness  and  deaths  that  are  due  to  the 
use  of  a  polluted  water. 

As  has  been  stated  by  the  excellent  authority  quoted 
above,  "the  health  of  a  community  always  improves 
when  an  abundant  and  pure  water-supply  is  given. 
The  death  of  3400  persons  from  cholera  followed  the 
temporary  supply  of  unfiltered  water  by  the  East  London 
Water  Company  in  1866,  while  the  rest  of  London  re- 
mained nearly  free  from  the  disease;"  and  in  1892  "Ham- 
burg lost  8605  citizens  from  the  same  disease  alone," 
regarding  which  "the  health  authorities  found  that  the 
principal  cause  of  this  epidemic  was  the  polluted  water- 
supply,"^  while  the  neighboring  city  of  Altona,  which  used 
filtered  water,  was  comparatively  free  from  the  disease. 

Again,  after  the  scourge  of  typhoid  fever  in  Plymouth, 

1  Hazen,  Filtration  of  Public  Water-supplies,  1895. 


180 


WATER 


Pa.,  in  1885,  when  there  were,  within  a  few  weeks,  1104 
cases  and  114  deaths  in  a  population  of  less  than  8000  as  a 
result  of  pollution  of  the  water-supply  by  a  single  person, 
great  care  was  taken  to  determine  the  exact  cost  of  the 
''visitation,"  as  some  would  term  it.  It  was  found  that 
the  actual  expenditure  for  the  care  of  the  sick  was 
$67,100.17;  loss  of  wages  by  those  recovering,  $30,020.08; 
a  total  of  $97,120.25,  to  which  should  be  added  a  number 
of  times  the  $18,419.52  that  those  who  died  were  earning 
per  annum  when  taken  sick.    How  much  cheaper  in  com- 


FiG.  52. — Portion  of  the  boundary  line  between  Hamburg  and  Altona. 
The  dots  indicate  cases  of  cholera.     (Harrington.) 


parison  would  a  protecting  filter-plant  have  been!  But 
overlooking  special  epidemics,  and  considering  the  average 
annual  typhoid  death-rates  of  our  cities,  we  find  that 
experience,  both  here  and  abroad,  shows  that  with  a  pure 
water-supply  a  maximum  death-rate  from  this  disease  is 
25  per  100,000,  and  that  any  city  may  reasonably  expect 
to  secure  even  a  lower  rate  by  observing  proper  pre- 
cautions. And  yet  thirty-one  cities  of  over  25,000 
population,  including  three  of  over  100,000  and  seven 
others   of   over   50,000,    whose    mortality    returns    were 


FINANCIAL  LOSS  DUE  TO  DISEASE  181 

given  in  the  United  States  Census  Reports  of  191()  had 
a  higher  rate  than  this,  seven  being  more  than  twice  as 
high. 

Lawrence,  Mass.,  with  a  population  of  44,654  in  1890, 
built  a  filter  at  a  cost  of  $67,000,  saved  enough  lives, 
at  $5000  per  head,  to  pay  for  it  within  the  first  four 
months  that  it  was  in  use,  and  had  a  reduction  of  almost 
60  per  cent,  in  the  typhoid  death-rate  within  a  year. 
In  Chicago,  when  the  similarly  estimated  loss  from 
typhoid  deaths  in  the  city  and  suburbs  amounted  to  over 
$10,000,000  in  1891,  the  abandoning  of  a  shore  inlet  near 
the  mouth  of  the  sewage-polluted  Chicago  River  in  1892 
resulted  in  a  reduction  of  60  per  cent,  in  the  typhoid 
mortality  during  the  following  year. 

But  it  is  only  when  one  realizes  that  an  increase  in  the 
mortality  from  any  cause  of  only  1  in  1000  of  population 
means  1000  additional  deaths  per  annum  in  a  city  of  a 
1,000,000,  that  he  can  appreciate  the  meaning  and  the 
loss  in  capitalization  to  the  municipality  of  the  exceedingly 
high  typhoid  mortality  that  obtains  in  some  of  our  large 
cities.  Philadelphia's  death-rate  from  this  disease  has 
dropped  from  an  average  of  61.3  per  100,000  of  population 
foreach  of  thefive  years,  1903-1907  inclusive,  to7.6  for  1916, 
the  installation  of  filter-plants  for  the  entire  water-supply  of 
the  city  having  been  begun  in  1902  and  completed  in  1911. 
This  represents  a  saving  of  918  typhoid  deaths  per  annum 
based  on  the  population  of  the  city  in  1916,  and  probably 
as  many  more  from  other  diseases  due  to  impure  water. 
At  the  valuation  of  $5000  per  capita — not  an  excessive 
estimate  according  to  the  finding  of  courts  in  cases  of 
death  by  accident,  and,  inasmuch  as  most  typhoid  cases 
occur  during  the  working  age  of  from  fifteen  to  fifty 
years — in  one  municipality,  with  an  average  population 
of  about  one-third  of  a  million,  the  excessive  typhoid 
deaths  above  a  25-per- 100,000  rate  amounted  in  five  years 
(1900-1904)  to  the  astounding  total  of  1888,  represent- 
ing in  capitalization  at  the  above  life  valuation  the  sum 
of  $9,440,000.     Nor   must   it   be   forgotten   that   these 


182  WATER 

figures  do  not  include  the  cost  of  medical  attention  and 
nursing  for  the  thousands  who  were  sick,  nor  the  loss 
of  time  and  employment  by  those  who  recovered,  nor  do 
they  consider  the  financial  loss  due  to  sickness  and  deaths 
from  diseases  other  than  typhoid  fever  that  may  be  fairly 
attributed  to  polluted  water-supplies.  Can  anyone  doubt 
where  true  municipal  economy  lies,  and  is  there  not 
abundant  opportunity  for  sanitary  education  and  work  in 
this  direction  alone  for  many  years  to  come?^ 

Purification  before  distribution  may  be  by  either  or  all 
of  three  methods:  subsidence,  chemical  treatment,  and 
filtration. 

Subsidence. — This  method  consists  in  allowing  the 
water  to  stand  in  large  reservoirs  until  the  greater  part 
of  the  suspended  matters  have  fallen  to  the  bottom.  If 
sufficient  time  be  given,  much  of  the  organic  matter, 
whether  solid  or  dissolved,  will  be  decomposed  or  reduced 
to  simpler  compounds  by  the  action  of  the  sunlight,  oxy- 
gen, animalculse,  saprophytes,  etc.  Most  of  the  bacteria 
also,  especially  the  pathogenic  species,  will  disappear 
either  by  sedimentation,  by  death  from  lack  of  favorable 
conditions,  or  on  account  of  the  germicidal  effect  of  the 
sunlight.  "The  great  source  of  ultra-violet  radiations 
and  'the  cheapest  disinfectant  known,'  as  Duclaux  puts 
it,  is  the  sun.  Rivers  and  lakes  are  freed  from  a  great 
part  of  their  bacterial  contents  by  the  bactericidal  powers 
contained  in  the  sun's  rays."^  Consequently,  a  water 
originally  quite  impure  may  be  much  improved  by  this 
method  alone,  while  if  it  is  used  in  conjunction  with,  and 
preliminary  to,  filtration  it  will  be  additionally  advantage- 

1  According  to  the  Report  on  Mortality  Statistics  of  the  U.  S.  Census 
Office  for  1916,  the  deaths  from  typhoid  fever  in  the  "registration-area" 
in  that  year  numbered  9,510.  The  typhoid  death-rate  for  the  entire 
"registration- area"  dropped  from  35.9  per  100,000  in  1900  to  13.3  in 
1916,  and  the  average  for  the  last  five  years  (1912-1916)  Was  14.75. 
This  is  higher  than  that  of  most  European  countries,  the  rate  for  Eng- 
land and  Wales  for  1905  being  8.9;  for  Germany,  6.3,  and  for  Norway, 
3.8  per  100,000. 

^  Von  Recklinghausen,  Journal  of  the  Franklin  Institute,  December, 
1914,  p.  683. 


I 


PURIFICATION  IN  RESERVOIRS 


183 


ous  in  that  it  reduces  the  cost  of  the  latter  by  lessening 
the  frequency  and  expense  of  cleaning  the  filters. 

What  the  capacity  of  the  reservoirs  and  the  time  of 
storage  should  be,  depend  on  circumstances.  If  it  is  the 
only  method  of  purification  employed,  and  especially  if 
the  water  is  very  foul,  the  longer  the  time  of  storage  the 
better.  Again,  if  the  source  of  supply  is  variable  in  out- 
put or  if  it  is  liable  to  excessive  pollution  for  limited 


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PHILADELPHIA,  PA.-TYPHOID  DEATHS 


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Fig.  53. — Chart    showing    the  influence  of   filtered  water  upon   the 
typhoid  death-rate  in  Philadelphia.* 


periods,  the  capacity  should  be  such,  if  possible,  that 
water  need  not  be  collected  during  the  emergency.  On 
the  other  hand,  if  the  water  is  to  be  subsequently  filtered, 
the  capacity  of  the  reservoirs  and  time  of  storage  need  not 
be  so  great.  Most  German  authorities  on  filtration  hold 
that  preliminary  sedimentation  for  twenty-four  hours  or 
even  less  is  sufficient,  most  of  the  solid  matters  being  pre- 

*  Figs.  53,  54,  55,  and  62  are  available  through   the  courtesy  of  the 
Bureau  of  Water  of  the  City  of  Philadelphia. 


184 


WATER 


cipitated  within  that  time,  if  at  all,  and  the  filters  being 
relied  upon  to  remove  the  remainder,  especially  the  finer 
particles  and  the  bacteria.  The  English  practise  is  to  store 
the  water  for  a  longer  time,  though  local  causes  related 
to  the  source  of  supply  are  the  reason  for  this.  Thus  the 
Lea  and  Thames,  from  which  the  London  companies  take 
much  of  their  water,  are  subject  to  extra  pollution  in 
times  of  flood,  which  are  usually  of  short  duration,  and  a 
sufficient  reserve  for  such  periods  is  of  obvious  value. 


400 


PHILADELPHIA,  PA, 
TYPHOID  CASES  PER  WEEK  1904,  1913  AND  1914 


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Fig.  54. — Chart  showing  the  reduction  in  rate  and  change  of  seasonal 
incidence  of  typhoid  fever  in  Philadelphia  following  the  general  supply 
of  filtered  water  to  the  entire  city. 


All  storage  reservoirs  should,  of  course,  be  kept  free 
from  extraneous  contamination,  and  should  be  cleaned 
from  time  to  time.  This  necessitates  an  arrangement  in 
pairs  or  groups,  or  a  partitioning  of  large  reservoirs,  so 
that  one  part  may  be  cleansed  without  putting  the  rest  out 
of  service.  Weeds  should  be  destroyed,  as  they  sometimes 
give  an  unpleasant  taste  to  the  water.    The  water  may  also 


CHEMICAL  TREATMENT  OF  WATER  185 

have  a  bad  taste  or  odor  from  algse  and  other  species  of 
minute  plants  which  especially  favor  a  pure  water  ex- 
posed to  sunshine.  They  are  not  known  to  be  harmful, 
but  it  may  be  necessary  to  cover  the  reservoirs  to  get  rid 
of  them  and  their  unpleasant  properties. 

By  the  creation  of  great  impounding  reservoirs  in  the 
Catskills,  New  York  City  is  providing  a  supply  which, 
taken  with  that  from  the  Croton  water-shed,  its  previous 
source  of  supply,  will  give  a  total  of  eight  hundred  million 
gallons  daily.  From  these  reservoirs  the  water  is  con- 
veyed for  119  miles  to  the  terminal  reservoir  on  Staten 
Island  through  the  greatest  aqueduct  ever  constructed, 
35  miles  of  it  being  through  solid  rock  far  below  the  sur- 
face, it  passing  under  the  Hudson  at  a  depth  of  almost 
1400  feet  below  the  river  level. 

Chemical  Treatment. — Where  a  water  is  very  hard  or 
contains  an  excess  of  mineral  matter  it  is  frequently  of 
advantage  to  treat  it  chemically.  If  the  hardness  is 
due  to  calcium  bicarbonate  in  excess,  it  may  be  removed 
by  the  addition  of  a  solution  of  calcium  hydroxide  to  the 
water,  insoluble  calcium  carbonate  being  formed  and  pre- 
cipitated.    The  change  is  represented  by  the  equation: 

CaH2(C03)2  +  Ca(0H)2  =  2CaC08  +  2H2O. 

Clark's  process,  based  on  this  reaction,  is  as  follows: 
About  fourteen  or  fifteen  hundred-weight  of  lime  is 
allowed  to  each  million  gallons  of  water,  the  actual  quan- 
tity of  lime  depending  on  the  amount  of  bicarbonate  in 
the  water.  The  lime  is  slaked  in  a  tank  into  which  the 
water  to  be  treated  flows;  the  mixture  is  well  stirred 
and  then  allowed  to  stand  for  from  three  to  twelve 
hours,  when  the  supernatant  water  is  drawn  off,  the  tank 
cleaned,  and  the  process  repeated.  "The  stirrmg  motion 
not  only  accelerates  and  completes  the  chemical  action, 
but  has  a  tendency  to  gather  together  the  fine  particles 
of  carbonate  of  lime  formed  by  the  softening  chemicals 
into  comparatively  large  masses  which  settle  with  great 
rapidity  as  soon  as  the   water  flows  into   the  settling 


USE  OP  ALUM  AS  A  COAGULANT  187 

tank."  The  water  is  not  only  softened  in  this  way, 
but  the  precipitate  also  usually  carries  down  with  it 
much  of  the  solid  impurities  and  organic  matter  in  the 
water.  This  process  is  extensively  used  in  England,  where 
much  of  the  available  water  is  derived  from  the  under- 
lying chalk-beds,  and  thus  has  a  superabundance  of  the 
bicarbonate;  but  the  writer  is  unaware  that  it  finds  any 
general  application  in  this  country,  though  it  might  be  an 
advisable  method  of  treatment  in  certain  pf  our  limestone 
districts. 

If  alum  (aluminum  sulphate)  be  added  to  an  impure 
water,  a  decomposition  of  the  salt  occurs,  the  acid  portion 
combining  with  the  bases  in  the  water  and  forming  a 
flocculent  precipitate  of  insoluble  basic  sulphates  and 
aluminum  hydroxide,  which  entangles  in  it  and  carries 
down  the  suspended  impurities  in  the  water,  beside 
removing  much  of  the  dissolved  organic  and  coloring 
matters.  Moreover,  careful  experiments  have  shown  that 
the  addition  of  only  about  one  grain  of  alum  per  gallon, 
followed  by  thorough  agitation  and  subsequent  settling 
for  twenty-four  hours,  will  almost  invariably  give  a  water 
free  from  germs  and  one  that  will  tend  to  remain  sterile 
for  a  considerable  time;  this  possibly  being  due  to  re- 
moval of  the  food-supply  of  the  bacteria.^ 

The  use  of  alum  is  especially  advantageous  when  a 
water  contains  a  very  fine  silt  or  the  like  in  suspension, 
and  which  is  not  removed  by  subsidence  even  after  a  con- 
siderable time.  It  is  also  to  be  used  in  conjunction  with 
or  preliminary  to  mechanical  filtration,  which  latter,  at  the 
usual  rate  of  operation,  is  oftentimes  practically  depend- 
ent upon  alum  for  the  furnishing  of  a  clear,  safe  water. 
Comparatively  little  alum  is  needed,  even  with  a  very 
dirty  water — usually  not  more  than  one  or  two  grains 
per  gallon,  and  if  the  supply  is  practically  adjusted  to 
the  condition  of  the  water,  as  it  should  be,  the  extremely 
minute  quantity  of  free  alum  that  may  sometimes  pass 
through  the  filters  is  harmless  and  unimportant. 

1  V.  and  A.  Babes,  Centralblatt  fiir  Bakteriologie  und  Parasitenkunde, 
1892,  vol.  ii,  No.  45. 


188  WATER 

Should  the  water  be  lacking  in  sufficient  bases,  which, 
however,  is  extremely  improbable,  it  might  contain  when 
filtered  a  very  little  free  acid,  which  can  be  readily  neu- 
tralized by  the  addition  of  a  correspondingly  small  quan- 
tity of  sodium  hydroxide  or  carbonate,  the  resulting  salt 
affecting  neither  the  healthfulness  nor  the  palatability  of 
the  water.  It  has  been  suggested  that  the  alum  be  first 
decomposed  by  the  addition  of  sodium  hydroxide,  then 
washed  free  from  the  resulting  sodium  sulphate  and  the 
flocculent  aluminum  hydroxide  added  to  the  water,  thus 
avoiding  the  chance  of  there  being  either  free  alum  or 
acid  in  the  cleared  water;  but  experiments  show  that  the 
results  are  not  so  good  as  when  alum  alone  is  used. 

Regarding  the  danger  from  the  use  of  water  purified 
by  the  addition  of  alum,  Hazen  says:  "Although  alum 
in  large  quantities  is  undoubtedly  injurious  to  health,  it  is 
neither  a  violent  nor  a  cumulative  poison;  and  the  propo- 
sition that  one  part  of  alumina  in  a  million  parts  of  water 
is  injurious  to  health  must  be  regarded  as  conjecture  rather 
than  as  a  matter  of  proof  or  even  of  probability." 

The  Anderson  process,  which  consists  in  agitation  of 
the  water  with  metallic  iron  before  filtration,  has  been 
employed  at  Antwerp  and  elsewhere;  but  it  is  not  clear 
that  with  large  quantities  of  water  better  results  are 
obtained  than  by  simple  filtration.  The  idea  is  that  some 
of  the  iron  is  converted  into  soluble  ferrous  carbonate, 
which  then  oxidizes  to  insoluble  ferric  hydroxide  and 
carries  down  with  it  the  suspended  and  many  dissolved 
impurities,  and  thus  facilitates  their  removal  by  sedimen- 
tation and  filtration.  The  difficulty  in  using  this  process 
on  a  large  scale  seems  to  be  that  the  carbonate  is  not 
formed  quickly  enough,  and  also  that  too  much  of  the 
iron  may  remain  in  solution  even  after  filtration. 

A  chemical  method  that  has  come  into  vogue  com- 
paratively recently  involves  the  addition  to  a  polluted 
water  of  small  quantities  of  the  hypochlorites,  especially 
that  of  calcium,  and  still  later  of  chlorin  alone.  To  quote 
from  an  experimental  study  of  the  process  by  E.  J.  Tully, 


USE  OF  HYPOCHLORITES  AND  CHLORIN        189 

of  the  University  of  Wisconsin,  "the  process  is  essentially 
one  of  oxidation,"  many  bacteria  and  much  organic 
matter  being  destroyed  by  the  nascent  oxygen  liberated 
in  the  reactions  occurring  when  the  hypochlorites  are 
added  to  water  containing  them.  His  conclusions  are  as 
follows:^ 

**  Chemical  disinfection  offers  a  means  whereby  a  very 
satisfactory  purification  of  water  may  be  accomplished. 
Comparisons  on  a  cost  basis  of  the  methods  of  chemical 
disinfection  make  it  apparent  that  calcium  hypochlorite 
is  the  most  satisfactory  and  efficient  agent  at  the  present 
time  for  water  disinfection. 

"  The  amount  of  organic  matter  in  the  water  practically 
determines  the  quantity  of  calcium  hypochlorite  that  it  is 
necessary  to  use.  As  a  general  rule,  practical  sterilization 
may  be  accomplished  by  the  application  of  from  0.1  to  1 
part  per  million  of  available  chlorin,  but  occasionally 
concentrations  of  2  and  3  parts  per  million  of  available 
chlorin  are  necessary  to  effect  desirable  results  with  rather 
highly  colored  and  turbid  .waters. 

"The  removal  of  B.  coli  and  intestinal  organisms  is 
usually  more  complete  than  that  of  the  total  organisms. 
Under  the  conditions  of  the  laboratory  experiments,  the 
results  of  the  hypochlorite  disinfection  on  typhoid  organ- 
isms and  intestinal  bacteria  in  the  various  waters  were 
practically  identical.  It  is  therefore  safe  to  assume 
that  the  viability  of  pathogenic  bacteria  under  working 
conditions  in  practical  water  disinfection  is  no  greater 
than  that  of  the  typhoid  organism,  or  intestinal  bacteria 
as  a  whole.  Consequently,  the  disinfection  effected  by 
calcium  hypochlorite  relative  to  the  total  bacterial 
removal  may  be  referred  directly  to  pathogenic  bacteria 
with  assurance  of  reasonable  accuracy. 

"The  slight  odor  and  taste  of  chlorin  imparted  when 
somewhat  more  than  0.5  part  per  million  is  applied  disap- 
pears in  a  short  time,  leaving  the  water  entirely  acceptable 

1  American  Journal  of  Public  Health,  May,  1914,  p.  435. 


190  WATER 

from  a  sanitary  stand-point;  and  as  the  hardness  is  not 
materially  increased  by  the  application  of  the  usual 
small  quantities  employed,  the  treated  water  is  not 
rendered  unsuitable  for  industrial  purposes. 

"There  is  no  apparent  reason  for  believing  that  the 
results  are  not  of  general  applicability.  The  reactions 
involved  are  particularly  free  from  interference  on  the 
part  of  the  mineral  constituents  of  normal  waters;  and 
normal  variations  of  temperature  have  no  effect  on  the 
final  results.  The  efficiency  of  the  process  is  also  entirely 
independent  of  the  secondary  or  after-growth  of  harmless 
resistant  organisms. 

"The  calcium  hypochlorite  process  of  sterilizing  water 
combines  the  desirable  qualities  of  economy  and  efficiency, 
and  affords  cities  and  towns  which  are  unable  financially 
to  build  a  filtration  plant,  but  are  forced  for  sanitary 
reasons  to  adopt  some  method  of  purification,  a  means 
of  ensuring  a  safe  water-supply.  It  may  be  used  to  ad- 
vantage in  cases  of  emergency,  where  either  filtered  or 
unfiltered  supplies  have  become  infected  and  where  it  is 
difficult  to  cease  using  such  supplies.  Where  mechanical 
filtration  is  not  sufficient  to  render  a  water  safe,  treatment 
with  calcium  hypochlorite  offers  an  excellent  method  of 
sterijization  and  is  especially  applicable  in  such  cases." 

Filtration. — For  the  purification  of  large  quantities  of 
water,  such  as  are  needed  for  great  cities,  there  can  be  no 
question  that  sand  filtration  is,  in  the  majority  of  cases, 
the  most  available,  satisfactory,  and  efficient  method, 
though  it  may  often  be  advantageously  preceded  by  sedi- 
mentation or  by  chemical  treatment,  as  already  described. 
The  former  especially,  by  removing  much  of  the  suspended 
matter,  will  prolong  the  use  of  the  filters  between  clean- 
ings and  thus  materially  lessen  the  cost  of  maintenance; 
while  the  latter  may  greatly  improve  the  chemical  quality 
of  the  filtered  water. 

Municipal  filters  of  the  type  to  be  described  are,  as 
yet,  not  sufficiently  well  known  in  this  country,  but  they 
have  been  used  abroad  with  increasingly  good  results 


FILTRATION 


191 


for  upward  of  half  a  century,  and  they  now  furnish  the 
daily  supply  of  water  to  many  millions  of  people. 
However,  we  may  take  credit   in  the  knowledge  that 


192 


WATER 


the  most  thorough  and  scientific  investigation  of  their 
action  and  efficiency  has  been  made  on  this  side  of  the 
Atlantic,  under  the  auspices  of  the  Massachusetts  State 
Board  of  Health,  and  that  it  is  to  this  body  that  we  are 
indebted  for  much  of  the  positive  information  that  we 
now  have  concerning  them. 

The  limitations  of  this  work  do  not  permit  a  full  dis- 
cussion of  the  principles  or  merits  of  such  filters,  but  the 
following  details  are  given  that  the  reader  may  appreciate 
the  simplicity  of  their  construction  and  the  efficiency  of 


„ Supply   to   Filters 


Supply   to  Mlteri  "         " 

Fig.  57.— Plan  of  filter-beds  at  Albany,  N.  Y. 


their  action.  Those  desiring  more  extended  information 
are  referred  to  the  Massachusetts  reports  that  discuss  this 
subject,  and  to  the  excellent  work  of  Hazen,  already 
mentioned,^  from  which  many  of  the  accompanying  state- 
ments and  illustrations  have  been  taken. 

Almost  without  exception  these  filters  now  consist  of  a 
layer  of  clean  sand  of  a  certain  degree  of  fineness  spread 
upon  a  layer  of  gravel  in  a  carefully  prepared  basin,  the 
whole  being  underdrained  and  proper  arrangements  made 


Filtration  of  Public  Water  Supplies. 


FUNCTIONS  OF  SEDIMENT-LAYER 


193 


for  the  controlling  of  the  depth  of  water  upon  the  surface, 
rate  of  flow  of  the  filtrate,  cleaning  of  filters,  etc.  Such 
filters  act  primarily  as  strainers,  to  remove  the  solid 
impurities  from  the  water,  but  their  efficiency  is  much 
increased  by  the  sediment  that  is  retained  upon  the  sur- 
face of  the  sand  and  that  forms  a  filter  or  "blanket"  much 
finer  than  the  latter  and  which  is  capable  of  mechanically 
preventing  the  passage  of  most  of  the  bacteria  always 
present  in  a  surface-water.  Moreover,  this  removal  of 
the  bacteria  is  often  largely  due  to  the  organisms  them- 
selves in  the  sediment-layer,  because  by  forming  a  felt- 
like growth  therein  they  not  only  increase  the  fineness 
of  the  strainer,  but  by  acting  as  saprophytes  they  also 
decompose  much  of  the  organic  matter  and  even  kill  the 


^^^^ 


Fig.  58. — General  arrangement  of  filter-plant.    (Hazen.) 


pathogenic  bacteria.  However,  it  now  seems  probable 
that  for  continuous  filters  the  action  is  sometimes  mainly 
mechanical,  consisting  in  the  removal  of  suspended 
matters  and  bacteria,  and  but  slightly  affecting  the  dis- 
solved organic  matters.  On  the  other  hand,  in  inter- 
mittent filtration,  where  the  conditions  more  nearly 
resemble  those  in  the  natural  soil  and  where  the  filters 
are  periodically  aerated,  the  straining  action  is  less  perfect 
on  account  of  the  greater  rate  of  filtration  necessary,  but 
the  nitrification  and  destruction  of  organic  matter  due 
to  the  action  of  the  saprophytes  and  oxygen  are  greater. 
Intermittent  filters,  therefore,  will  probably  prove  to  be 
the  better  for  the  purification  of  sewage  or  a  very  impure 
water,  though  usually  their  efficiency  in  removing  bacteria 
seems  to  be  inferior  to  that  of  continuous  filters. 
13 


194 


WATER 


The  location  of  the  filter-beds  with  respect  to  the 
source  of  supply  and  the  storage  reservoirs  will  depend 
largely  on  local  conditions,  cost  of  pumping,  etc.  Settling 
basins  are  almost  essential  where  the  water  to  be  fil- 
tered is  very  turbid,  even  if  only  at  intervals.  Refer- 
ence has  already  been  made  to  the  difference  of  opinion 
between  English  and  Continental  authorities  regarding 
the  size  of  these  settling  basins. 

Inasmuch  as  it  is  needful  to  govern  the  depth  of  the 
water  upon  the  filter-beds  according  to  the  rate  of  flow 
desired,  the  thickness  and  resistance  of  sand,  etc.,  and  to 
prevent  disturbance  of  the  sand  and  sediment  layer  by 


0  6  10  15  20  Feet 

Fig.  59. — Regulation  of  inflow  used  at  Hamburg.    (Hazen.) 


the  force  of  the  entering  current,  some  method  of  regu- 
lating the  inflow  is  required.  The  accompanying  illus- 
tration shows  a  comparatively  simple  arrangement  for  this 
purpose.     (Fig.  59.) 

The  total  area  of  the  fllter-beds  will  depend  upon  the 
amount  of  water  supplied,  the  rate  of  filtration,  and  the 
proportion  of  area  out  of  use  while  being  cleaned.  The 
total  area  is  to  be  divided  into  beds,  varying  in  number 
according  to  circumstances,  so  that  one  or  more  of  these 
beds  may  be  cleaned  while  the  rest  are  in  use.  Large 
beds  decrease  the  cost  per  acre  on  account  of  less  masonry, 


CONSTRUCTION  OF  FILTER-BEDS 


195 


etc.,  being  needed,  but  it  may  be  more  difficult  to  main- 
tain an  even  action  over  large  areas.  At  the  Torresdale 
filtration  plant  in  Philadelphia,  which  is  the  largest  in 


Fig.  60. — Interior  of  a  covered  filter  ready  for  use. 

the  world,  and  has  a  capacity  of  240  million  gallons  of 
filtered  water  per  day,  the  area  of  each  of  the  sixty-five 


Fig.  61. — Sectional  plan  of  a  covered  filter. 


slow  sand  filters   is  approximately   three-fourths   of   an 
acre,  and  the  individual  area  of  the  beds  at  the  other 


196  WATER 

filtration  stations  of  that  city  vary  from  this  to  a  little 
more  than  one-half  acre.  Evenness  of  action  is,  however, 
largely  governed  by  the  size  and  arrangement  of  the 
underdrains. 

The  walls  and  bottoms  of  filter-beds  should  be  made 
water-tight,  that  there  may  be  no  waste  of  the  filtered 
water  on  the  one  hand,  nor  any  ingress  of  foul  soil-water 
on  the  other.  The  shape  of  the  filter-bed  is  immaterial, 
provided  evenness  of  work  over  the  whole  area  is  not 
impaired.  Where  the  mean  January  temperature  is  below 
the  freezing-point  the  beds  should  be  covered,  as  the  for- 
mation of  ice  upon  them  seriously  impairs  their  efficiency, 
and  as,  moreover,  a  number  of  epidemics  of  typhoid  fever 
and  certain  intestinal  diseases  seem  to  be  directly  traceable 
to  ice-formation.  This  may  have  been  on  account  of  the 
overtaxing  of  the  filters  through  increased  difficulty  in 
working,  or  because  the  sediment  layer  and  the  sand  were 
disturbed  in  the  removal  of  the  ice. 

As  already  stated,  the  materials  used  practically  every- 
where are  clean  sand  and  gravel,  and  the  sharper  the 
sand-grains  the  better.  At  the  Lawrence  Experiment 
Station  of  the  Massachusetts  State  Board  of  Health  "the 
size  of  a  sand-grain  is  uniformly  taken  as  the  diameter  of 
a  sphere  of  equal  volume,  regardless  of  its  shape."  More- 
over, as  it  is  "  the  finest  portion  which  mainly  determines 
the  character  of  sand  for  filtration,"  the  effective  size  is 
taken  to  be  "  the  size  of  a  grain  such  that  10  per  cent,  by 
weight  of  the  particles  are  smaller  and  90  per  cent,  are 
larger  than  itself."  As  uniformity  of  grain  is  also  im- 
portant, the  uniformity  coefficient  is  "the  ratio  of  the  size 
of  grain  which  has  60  per  cent,  of  the  sample  finer  than 
itself  to  the  size  which  has  10  per  cent,  finer  than  itself." 
Obviously,  the  velocity  of  water  through  a  layer  of  sand 
will  depend  upon  the  effective  size  of  the  grain,  the  thick- 
ness of  the  layer  through  which  the  water  passes,  and  the 
loss  of  head  due  to  the  frictional  resistance  of  the  sand. 
A  rise  in  temperatures  causes  a  progressive  increase  in 
velocity. 


MATERIALS  FOR  FILTER-BEDS  197 

The  effective  sizes  of  sand-grain  in  use  in  most  of  the 
foreign  filters  average  from  0.31  to  0.4  mm.  In  general, 
it  may  be  said  that  the  finer  the  sand  the  better  is  the 
quality  of  the  normal  filtrate  and  the  less  the  danger  of 
an  unsafe  effluent  in  case  the  sediment  layer  on  top  of 
the  sand  is  broken;  but,  on  the  other  hand,  cost  of  filtra- 
tion increases  with  the  smallness  of  sand-grain,  since  the 
filters  must  be  cleaned  oftener  and  fine  sands  are  harder 
to  wash,  as  well  as  because  the  velocity  of  flow  is  slower 
through  fine  sands.  AH  things  considered,  the  best  results 
will  probably  be  obtained  with  a  sand  having  a  uniformity 
coefficient  of  not  more  than  3 — the  lower  the  better — and 
an  effective  size  of  from  0.2  to  0.35  mm.,  the  latter 
depending  largely  upon  the  character  and  clearness  of 
the  water  to  be  filtered. 

The  thickness  of  the  sand  layer  should  be  such  that  it 
may  be  scraped  a  number  of  times  before  becoming  so 
thin  as  to  require  replacing.  The  German  Imperial  Board 
of  Health  requires  a  thickness  of  at  least  twelve  inches 
after  the  last  scraping;  while  the  original  thickness  should 
be  from  twenty-four  to  forty-eight  inches — the  thicker  the 
better — provided  the  cost  of  the  filter  be  not  made  too 
great  and  the  rate  of  filtration  be  not  too  much  dimin- 
ished. The  sand  should  be  of  the  same  degree  of  fine- 
ness throughout. 

As  for  the  gravel  beneath  the  sand,  there  is  no  reason 
why  it  should  be  of  excessive  thickness.  A  depth  of  one 
foot  is  probably  sufficient,  provided  the  stones  are  of 
varying  size,  so  arranged  that  the  sand  above  will  not 
work  into  and  through  the  interstices,  and  that  the  water 
may  freely  enter  the  underdrains  at  low  velocity.  The 
loss  of  head  in  water  flowing  through  a  thin  layer  of 
gravel  properly  placed  is  comparatively  slight.  Foreign 
filters  do  have  a  gravel  layer  of  two  feet  or  more  in  thick- 
ness, as  a  rule,  but  careful  experiments  at  Lawrence, 
Mass.,  show  that  this  depth  is  unnecessary,  provided  that 
the  gravel  is  properly  laid  as  indicated,  and  that  the 
underdrains  are  not  too  far  apart. 


WATER 


The  underdrains  should  be  of  such  size  and  so  con- 
structed that  the  frictional  resistance  which  they  offer  to 
the  flow  of  the  water  is  only  a  small  percentage  of  that  of 


UNDER-DHAINS  IN  FILTER-BEDS 


199 


the  clean  sand,  and  that  the  rate  of  filtration  is  the  same 
over  the  whole  area  of  the  filter.  There  is  usually  a  main 
drain  along  the  middle  of  the  filter-floor  with  smaller  par- 
allel lateral  drains  leading  into  it  at  regular  intervals. 
The  drains  may  be  made  of  brick  with  open  joints,  or, 
for  the  laterals,  of  tile,  which  is  usually  cheaper.  Care 
must  always  be  had  that  the  openings  are  sufficient  in 
number  and  size  to  admit  the  water  freely. 

The  area  drained  should  vary  from  about  300  square 
feet  for  a  4-inch  lateral  drain  to  4400  square  feet  for  a 
12-inch  main,  the  velocity  of  flow  in  these  being  respec- 


'-^t-.^^!^     '',     -i^ 


112  3  4  5  6  7 


SMetets 
J 


Fia.  63. — Simplest  form  of  regulating  outflow  from  filter-beds.    Stralau 
filters  at  Berlin.     (Hazen.) 


tively  0.3  and  0.51  foot  per  second;  while  larger  drains 
should  have  a  cross-section  of  at  least  one-six-thousandth 
of  the  drained  area.  The  European  custom  of  ventilat- 
ing drains  by  means  of  pipes  passing  up  through  the 
sand  and  water  above  is  not  to  be  commended,  since 
such  ventilation  apparatus  is  unnecessary,  increases  the 
cost  of  the  filters,  and,  what  is  worse,  may  allow  im- 
purities to  contaminate  the  filtered  water  in  the  under- 
drains. 

Recently  it  has  been  suggested  that  the  filter-beds  be 
constructed  directly  over  the  storage  reservoirs  for  the 


200  WATER 

filtered  water,  the  beds  being  supported  on  suitable 
columns  resting  on  concrete  foundations  in  the  bottom  of 
the  reservoirs.  The  bottom  of  the  filter  may  be  of  im- 
pervious concrete,  as  it  is  in  the  Queen  Lane  filter  in 
Philadelphia,  or  pervious  to  allow  the  filtrate  to  be 
aerated  as  it  falls  through  the  intervening  space  above  the 
water  in  the  reservoir  below.  Theoretically,  it  would 
seem  that  the  latter  plan  is  a  good  one,  and  actual  results 
indicate  that  it  practically  is  so.  Some  of  its  advantages 
are  the  absence  of  underdrains  and  loss  of  the  resist- 
ance factor  due  to  them,  the  aeration  of  the  filtrate  as 
indicated,  and  also  the  practically  continuous  aeration 
of  the  filter-bed  itself,  thus  enabling  the  saprophytic 
bacteria  in  the  upper  layers  to  carry  on  their  work  of 
oxidizing  and  nitrifying  the  organic  impurities  of  the 
water.  One  serious  objection  to  such  a  filter  is  that  an 
accidental  overflow  would  contaminate  at  once  all  the 
filtered  water  in  the  storage  reservoir.  An  additional 
advantage  of  either  type  is  the  utilization  of  former 
sedimentation  reservoirs  that  are  supplanted  by  the 
filters,  especially  where  economy  of  space  is  desirable  or 
sufficient  adjacent  area  is  unobtainable  or  too  costly. 

Although  it  has  been  the  custom  to  keep  the  depth  of 
water  upon  the  filter-beds  in  excess  of  the  loss  of  head, 
this  is  not  essential.  On  foreign  filters  the  usual  depth  is 
from  36  to  52  inches,  though  less  than  this  might  suffice 
in  many  instances.  The  necessity  of  regulating  the  inflow 
and  outflow  and  of  maintaining  a  constant  level  must  not 
be  overlooked  if  uniform  results  are  desired. 

Summarizing  the  preceding  statements,  the  loss  of  head 
and  rate  of  filtration  will  depend  upon  the  depth  of  water 
on  the  filters,  the  thickness  of  the  sand  layer,  size  of 
sand-grains,  resistance  of  underdrains,  temperature,  etc., 
and  all  these  will  likewise  affect  both  the  cost  and  the 
efficiency  of  the  filtration. 

Where  the  water  is  taken  directly  from  a  river,  or  if 
the  opportunity  for  sedimentation  has  been  brief,  2,000,000 
gallons  per  acre  per  day  will  probably  be  a  safe  rate  of 


RATE  OF  FILTRATION  201 

filtration  to  maintain  continuously,  though  with  a  clear 
water  or  in  emergencies  a  rate  one-half  greater  will  very 
likely  not  materially  alter  the  quality  of  the  filtered  water 
or  increase  the  risk.  But  in  general  as  the  rate  increases 
the  efficiency  decreases.  However,  very  careful  and 
thorough  experiments  preliminary  to  the  construction  of 
the  Philadelphia  filters  and  practical  experience  since, 
have  shown  that  in  the  case  of  some  waters,  at  least, 
the  rate  may  safely  be  increased  to  even  5,000,000  and 
sometimes  to  almost  6,000,000  gallons,  provided  the 
water  be  first  passed  through  a  sedimentation  basin  and 


Fio.  64. — Sand   ejector  in    service.       (Philadelphia   Bureau   of   Water, 
description  of  the  filtration  works  and  pumping  stations,  1909.) 

a  so-called  '* preliminary'  or  ''rough  filter"  made  of  such 
materials  as  crushed  furnace  slag,  coke  breeze  or  coarse 
sand  or  gravel.  In  the  latter  much  of  the  suspended 
matter  that  has  passed  through  the  sedimentation  basin 
will  adhere  to  the  innumerable  surfaces  of  the  coarse  and 
porous  material  constituting  the  "preliminary  filter," 
thus  lessening  the  load  and  prolonging  the  action  of  the 
real  filters  through  which  the  water  now  passes.  The 
"preliminary  filters''  are  cleaned  by  agitation,  washing 
and  removal  from  time  to  time  of  the  contained  materials. 


202  WATER 

As  the  sediment  accumulates  and  deepens  upon  the  sur- 
face of  the  sand  the  rate  of  flow  necessarily  diminishes, 
and  it  becomes  necessary  after  a  time  to  remove  the 
deposit.  This  may  be  done  by  carefully  scraping  off  the 
top  layer  of  the  sand  to  the  depth  of  from  one-half  to 
one  and  one-half  inches,  removing  the  sand  to  platforms 
outside  the  filter  and  thoroughly  washing  it  with  a  stream 
of  filtered  water  under  pressure  or  by  passing  it  through 
one  or  more  sand  washers.    The  sand  need  not  be  replaced 


Fig.  65. — McNichol's  sand  separator  in  operation.  (Philadelphia 
Bureau  of  Water,  description  of  the  filtration  works  and  pumping 
station,  1909.) 

immediately,  for  the  filter  may  be  scraped  a  number  of 
times  before  the  layer  of  sand  above  the  underlying 
gravel  becomes  too  thin.  The  accumulation  of  sand  on 
the  washing  platforms,  which  has  been  exposed  to  the 
action  of  the  sunlight  and  air,  is  then  carefully  replaced, 
packed,  and  levelled  upon  the  beds.  These  do  not  again 
attain  their  greatest  efficiency  until  a  certain  amount  of 
sediment  from  the  water  has  once  more  collected  upon 
them,  and  it  is  therefore  not  advisable  to  use  the  filtered 
water  for  some  time  after  the  cleaning  and  until  bac- 


BACTERIOLOGICAL  AND  CHEMICAL  TESTS     203 

teriological  tests  show  that  the  maximum  purification  is 
being  attained. 

To  economize  in  manual  labor,  the  sand  may  be  trans- 
ported to  the  washing  platform  or  the  sand  washers  by 
means  of  a  sand  ejector  whereby  the  sand  is  carried  by  a 
forcible  stream  of  water  supplied  through  a  line  of  fire 
hose,  the  sand  being  partially  cleansed  while  in  transit. 
By  the  use  of  a  sand  separator  the  sand  may  be  cleaned 
without  removing  it  from  the  limits  of  the  filter-bed. 
The  separator  consists  of  a  closed  steel  cylinder  with  a 
cone-shaped  bottom,  and  within  which  is  arranged  a 
system  of  baffles  and  a  disc.  The  sand  is  forced  into 
this  from  the  sand  ejector,  there  being  a  down-flowing 
stream  of  sand  and  an  up-flowing  stream  of  wash-water 
so  proportioned  that  no  sand  is  lost  in  the  wash-water, 
which  is  carried  away  from  the  top  of  the  separator  and 
out  of  the  filters  to  the  sewers,  while  the  cleaned  sand  is 
discharged  from  the  bottom  and  distributed  through 
a  hose  on  top  of  the  filter-bed  where  it  is  spread  and 
levelled  by  manual  labor. 

An  essential  in  the  management  of  all  large  filters  is 
the  daily  bacteriological  and  chemical  examination  of  both 
the  filtered  and  unfiltered  water.  This  not  only  serves  to 
give  warning  of  any  accident  to  the  filter,  but  is  neces- 
sary, as  the  best  test  of  the  efficiency  of  a  sand  filter  is 
the  percentage  of  bacteria  which  it  takes  from  unfiltered 
water.  Unless  a  filter  is  holding  back  from  98  to  99  per 
cent,  or  more  of  the  bacteria,  it  needs  close  inspection, 
although  it  must  be  remembered  that  it  is  more  difficult 
to  get  good  results  with  a  badly  polluted  water  than  with 
one  that  is  comparatively  pure.  The  presence  of  the 
colon  bacillus  in  the  filtered  water  demands  additional 
effort  and  care,  or,  perhaps,  subsequent  chemical  treat- 
ment with  calcium  hypochlorite  or  chlorine.  In  Phila- 
delphia the  addition  of  one-half  pound  of  chlorine  to  one 
million  gallons  of  filtered  water  {i.  e.,  1  part  in  16  millions) 
seems  to  entirely  eliminate  all  trace  of  this  organism. 

Mechanical  Filters.^-Where  a  water  contains  a  very 
fine  sediment  or  silt  in  large  quantities,  the  sand-bed 


204  WATER 

may  be  clogged  and  choked  in  a  few  hours  and  before 
there  is  time  for  the  formation  of  the  bacterial  film  men- 
tioned above,  and  the  filtration  must  be  more  mechanical. 
For  example,  at  New  Orleans,  where  the  Mississippi 
River  contains  an  enormous  amount  of  a  silt  so  fine 
that  much  of  it  is  submicroscopic  and  many  of  the 
particles  even  smaller  than  bacteria,  the  water  is  pumped 
from  the  river  to  a  sedimentation  basin  capable  of  hold- 
ing twenty-four  hours'  supply,  through  which  it  passes 
slowly,  leaving  the  coarser  and  heavier  sediment;  then 
to  a  mixing  basin,  where  alum  is  added  as  a  coagulant 
to  an  extent  not  exceeding  six  grains  per  gallon,  and  then 
to  the  sand  filter-beds.  The  "blanket"  is  thus  formed 
by  the  coagulum  due  to  the  alum  which  commingles  with 
and  holds  the  silt,  preventing  the  latter  from  entering  and 
choking  the  filter.  The  filter-beds  are  cleaned  daily  or 
oftener  by  forcing  from  below^  first  a  liberal  washing  of 
filtered  water  and  then  a  supply  of  air.  The  cost  of  this 
treatment  is  about  $600  per  day  for  a  supply  of  40,000,000 
gallons. 

As  the  filtration  does  not  remove  hardness  due  to  dis- 
solved minerals,  it  may  also  be  advisable  to  use  the  Clark 
process  previous  to  sedimentation  and  filtration.  Part  of 
the  color  due  to  peat  or  vegetable  matters  is  removed  by 
ordinary  filtration,  and  still  more  may  sometimes  be  de- 
stroyed by  the  previous  addition  of  alum,  but  such  pre- 
liminary treatment  for  this  purpose  is  unusual.  Where 
the  water  comes  from  a  lake  or  from  a  river  with  a  slow 
current,  settling  basins  are,  of  course,  unnecessary,  but 
any  chemical  treatment  of  the  water  prior  to  filtration 
practically  implies  the  use  of  mechanical  instead  of  slow 
sand  filters  because  the  action  of  the  chemicals  necessarily 
destroys  or  eliminates  the  saprophytic  bacteria  which  are 
so  essential  to  the  proper  action  and  efficiency  of  the  slow 
sand  filter. 

Mechanical  filters  consist  essentially  of  large  cylindrical 
vats  or  tanks  (containing  rather  coarse  sand  or  crushed 
quartz  through  which  the  water  passes  by  gravity  or  is 
forced  by  the  pressure  in  the  supply  main  much   more 


MECHANICAL  FILTERS 


205 


rapidly  than  through  the  type  already  described.  Alum 
commonly  is  used  as  a  coagulant  to  form  precipitate  which 
entangles  and  retains  the  suspended  matter,  including 
microorganisms  and  other  particles  of  the  smallest  size,  and 
which  thus  does  the  work  of  the  bacterial  "  blanket"  of  the 
slow  sand  filter.  "  Ferrous  sulphate  and  lime  may  be  ad- 
vantageously used  in  certain  special  cases,  but  all  coagulants 
possess  the  power  of  gathering  together  the  finer  particles 


Fig.  66. — Mechanical  filter,  showing  revolving  forks  or  rakes,  and  also 
the  system  of  strainers  below  through  which  filtered  water  is  forced 
upwards  to  clean.se  the  filter-bed.     (Courtesy  of  Hungerford  and  Terry.) 


of  matter  into  comparatively  large  masses  so  that  sedimen- 
tation proceeds  at  a  very  rapid  rate."  The  supply  of 
alum  must,  of  course,  be  proportioned  to  the  amount  of 
suspended  matter  in  the  water,  being  delivered  in  solu- 
tion through  regulating  valves  to  a  mixing  tank  or  to 
the  filter  vats  directly.  The  accumulated  precipitate 
and  sediment  must  be  removed  at  comparatively  short 
intervals,  as  the  filters  soon  clog  and  the  supply  of  filtered 


206  WATER 

water  rapidly  lessens.  The  cleansing  of"  the  filters  is 
accomplished  by  forcing  a  reverse  current  of  filtered 
water  from  the  bottom  of  the  tank  while  the  sand  is  at 
the  same  time  thoroughly  stirred  by  forks  on  revolving 
arms  driven  by  machinery;  hence  the  term  "mechanical." 
"The  coagulant  must  be  fed  with  extreme  accuracy. 
If  a  deficiency  is  used,  the  desired  results  are  not  attained. 
If  an  excess  is  used,  the  chemicals  are  not  all  decomposed 
and  free  sulphate  of  alumina  becomes  present  in  the 
filtered  water."  A  small  amount  of  this  in  the  water 
may  not  be  important  as  regards  human  consumption, 
but  may  be  so  in  certain  commercial  processes,  such  as 
dyeing,  etc.  Such  filters  are  probably  not  quite  as 
efficient  in  purification  and  are  usually  more  expensive 
to  maintain  than  the  slow  sand  filters,  but  with  certain 
waters  this  type  only  can  be  used  effectively. 

DOMESTIC  PURIFICATION  OF  WATER. 

Boiling  destroys  living  organisms  and  disease  germs; 
it  also  drives  off  the  carbon  dioxide  and  other  gases  of  the 
water  and  causes  the  precipitation  of  many  mineral  sub- 
stances held  in  solution  by  these  gases.  This  is  especially 
the  case,  as  has  been  stated,  where  the  water  is  hard  from 
the  presence  of  calcium  bicarbonate  in  excess;  but  iron  is 
also  often  thrown  down  by  boiling.  If  the  water  contains  a 
very  fine  sediment,  not  removed  by  settling  or  filtration,  it 
may  be  advantageous  to  add  a  little  alum  and  chalk  to  pro- 
duce the  flocculent  precipitate  already  described .  Potassium 
permanganate  has  little  effect  in  purifying  a  foul  water. 
Agitation  with  iron  filings  may  do  a  little  good  by  favor- 
ing oxidation  of  organic  matters.  Tannin  is  believed  to 
destroy  microorganisms,  and  a  harmful  water  may  some- 
times be  made  usable  by  boiling  with  tea-leaves  or  other 
astringents.  Citric  acid  is  said  to  destroy  algse  and  many 
kinds  of  bacteria.  Aeration  and  agitation  improve  a 
water  after  distillation  or  boiling  by  restoring  oxygen  and 
also  by  oxidizing  organic  matters.    Remember  that  boiled 


DOMESTIC  PURIFICATION  OF  WATER 


207 


water  is  prone  to  take  up  gases  of  any  kind,  whether 
impure  and  offensive  or  otherwise.  Organic  matters  are 
removed  by  boiling,  exposure  to  air,  agitation,  addition 
of  alum,  astringents,  charcoal,  etc.;  calcium  bicarbonate, 
by  boiling  or  by  adding  caustic  or  slaked  lime  or  a  little 
sodium  hydroxide  or  sodium  carbonate;  iron,  by  boiling 
and  by  adding  lime-water.     According  to  Parkes  and 


FiQ.  67. — Water  sterilizer  for  schools,  factories,  etc.:*  a.  Supply  pipe; 
h,  steam  coil;  c,  thermometer;  c,  e,  corrugated  and  perforated  metal 
plates;  /,  /,  air  openings  guarded  by  cheese-cloth;  4,  tap  to  admit  cooling 
water  around  g,  g,  the  storage  tanks. 

Rideal,  fifteen  grains  of  acid  sodium  sulphate  to  the  pint 
(1  in  500)  will  destroy  typhoid  bacilli  in  five  minutes. 
Calcium  and  magnesium  sulphates  and  chlorides  cannot 
readily  be  removed.  Some  plants  help  to  purify  by 
means  of  the  oxygen  which  they  give  to  the  water. 

1  From  the  Bulletin  of  the  Chicago  Health  Department,  Sept.  19,  1903. 


208 


WATER 


Distillation  gives,  of  course,  a  water  free  from  harmful 
impurities,  but  one  which  has  lost  it  gases,  and  which 
may  be  improved  in  palatability  by  aeration  or  by  being 
charged  with  carbon  dioxide  gas.  Stills  for  domestic  use, 
capable  of  supplying  an  abundance  of  water  for  drinking 
and  cooking  purposes,  can  now  be  purchased  at  moderate 
cost.  The  main  objection  to  distillation  in  the  household 
is  that  the  process  is  somewhat  slow  and  tedious. 


^^^^ 


Fig.  68. — Section  of  domestic  still. 


Comparatively  recently  an  apparatus  has  been  invented 
and  introduced  which  furnishes  a  boiled  water  free  from 
disease  germs,  yet  unchanged  in  taste  by  the  boiling,  and 
at  nearly  the  same  temperature  as  the  water  entering  the 
apparatus.    This  is  the  Forbes  (formerly  the  Waterhouse- 


BOILING  AND  DISTILLATION 


209 


Forbes)  sterilizer.  The  principles  involved  in  its  con- 
struction and  operation  are  that  only  a  small  bulk  of 
water  is  being  boiled  at  any  instant;  that  it  is  boiled 
for  only  a  very  short  time,  thus  preventing  loss  of  the 
original  gases  and  taste;  that  all  disease  germs  are  killed 
by  the  boiling;  that  it  is  impossible  for  water  which 


Fig.  69. — Diagrammatic  representation  of  the  principle  of  the  Forbes 

sterilizer. 

has  not  been  boiled  to  pass  through  the  apparatus;  and 
that  the  heat  of  the  boiled  water  is  used  to  warm  the 
unboiled  water  (thus  economizing  fuel)  at  the  same  time 
that  the  latter  is  made  to  cool  the  former. 

Reference  to  the  diagram  (Fig.  69)  shows  that  the  water 
can  rise  no  higher  than  the  level  X  until  it  ''boils  over'' 
through  the  spout  a  into  the  receiver  h.    The  interchange 
14 


210 


WATER 


of  heat  takes  place  through  the  diaphragm  c,  which  in  the 
apparatus  itself  is  very  thin  and  corrugated,  so  as  to 


INSIDE  SHELL 

MIDDLE  SHELL- 
RAW  WATER 


ATCHALL 


FOUNTAIN  TUBE 


OUTSIDE  SHELL- 
STERILE  WATER-b- 


HEATER 
BUNSEN  BURNER 


-STERILE  WATER  OUTLET 
Fig.  70. — Forbes's  sterilizer. 


THE  FORBES  STERILIZER  211 

expose  large  surfaces  to  the  water  on  the  two  sides  of  it, 
the  entering  water  in  the  ascending  column  thus  absorb- 
ing practically  all  the  heat  from  the  boiled  water  in  the 
descending  column  and  being  almost  at  the  boiling-point 
by  the  time  it  is  over  the  flame. 

This  apparatus  is  furnished  in  a  suitable  size  for  house- 
hold use.  It  is  also  made  on  a  large  scale  and  in  a  con- 
venient form  for  transportation,  having  been  adopted  by 
the  United  States  Army  as  being  "well  adapted  to  the 
abundant  supply  of  sterile  water  for  troops  in  the  field." 
The  Board  of  Medical  Officers  appointed  at  the  time 
of  the  Spanish-American  War,  by  the  Surgeon-General  of 
the  Army  to  consider  the  filters  and  other  apparatus  of 
the  kind  submitted  made  the  following  report: 

"The  advantages  of  this  most  ingenious  water  steril- 
izer are:  First.  That  water  passing  through  it,  although 
brought  to  the  boiling-point,  is  maintained  at  this  tem- 
perature for  so  short  a  time  as  not  to  be  deprived  of  its 
natural  gases,  and  hence  not  rendered  unacceptable  to  the 
taste.  Second.  That  all  living  microorganisms  .  .  . 
are  destroyed  by  the  degree  of  heat  attained  during  the 
passage  of  the  water  through  the  apparatus.  Third.  It 
furnishes  an  abundant  supply  of  practically  sterile  water, 
and  may  be  kept  in  action,  if  necessary,  for  the  entire 
twenty-four  hours  without  renewing  the  supply  of  oil  in 
the  reservoir,  and  at  a  cost  of  about  one-fourth  of  a  cent 
an  hour.  Fourth.  The  water,  having  been  slowly  heated 
until  it  reaches  temporarily  the  boiling-point,  is  afterward 
cooled  to  within  4°  or  5°  F.  of  the  water  entering  the 
apparatus.  This  is  one  of  the  important  advantages  pos- 
sessed by  this  sterilizer.  By  placing  the  bottom  of  the 
exchange  in  a  freezing  mixture  the  temperature  of  the  ster- 
ilized water  as  it  flows  from  the  machine  may  be  reduced 
below  40°  F.  Fifth.  Its  durability  and  freedom  from 
liability  to  breakage.  Sixth.  The  facility  with  which  the 
apparatus  may  be  put  together  and  entirely  taken  apart; 
only  one  tool,  a  wrench,  being  required  for  this  purpose. 
Seventh.  The  facility  with  which  the  apparatus  can  be 


212 


WATER 


thoroughly  cleansed.  This  is  effected  by  the  removal  of 
the  rubber  cocks,  thus  permitting  a  complete  flushing  out 
of  both  exchanges.  The  fact  that  the  apparatus  does  not 
clarify  the  water  is  also  deemed  of  no  particular  impor- 
tance by  the  Board,  since  this  may  be  easily  effected  prior 
to  its  passage  through  the  sterilizer  by  means  of  one  or 
two  water  barrels  partially  filled  with  fine  and  coarse  sand 
and  placed  at  a  proper  height  above  the  sterilizer.  As  a 
result  of  exhaustive  experiments  ...  the  Board  is  of  the 
opinion  that  this  sterilizer  is  superior  to  all  filters  or  other 
water  sterilizers  submitted  for  trial.  We  therefore,  after 
a  careful  consideration  of  the  requirements,  respectfully 
recommend  that  the  Forbes  sterilizer  be  issued  for  the 
use  of  troops  serving  in  the  field." 

In  recent  years  the  use  of  the  above-described  sterilizer 
has  been  superseded  in  the  U.  S.  Army  by  the  Lyster 
water-bag  which  is  more  convenient  for  transportation, 
and  by  means  of  which,  advantage  is  had  of  the  steriliz- 
ing effect  of  calcium  hypochlorite.  For  dwellings  or 
permanent  stations,  however,  the  Forbes  sterilizer  remains 
an  excellent  device  for  securing  a  safe  water-supply. 
For  a  description  of  the  Lyster  bag  see  page  476. 


Fig.  71. — Tubes  of  unglazed  porcelain  for  Pasteur-Chamberland  filter. 


House  filters  are  dangerous  unless  properly  cared  for, 
and  may  give  more  and  worse  impurities  to  the  water 
than  they  take  from  it.  What  a  filter  takes  from  a  water 
is  left  in  the  filter  unless  otherwise  removed,  and  an  accu- 
mulation of  such  impurities  cannot  improve  the  water 
passing  through  them.  The  organic  matters  will  undergo 
decomposition  and  putrefaction,  and  will  furnish  a  good 
culture-medium  for  bacteria,  and  these,  together- with  the 


HOUSE  FILTERS 


213 


soluble  putrefaction-products,  will  in  most  cases  be  carried 
through  the  filter  with  and  by  the  filtered  water.  A  filter 
has  no  miraculous  power  to  annihilate  filth  and  the  size 
of  a  filter  must  always  limit  the  work  it  can  do,  whatever 
the  materials  used. 

According  to  Parkes,  the  requisites  of  a  good  filter  are: 
(1)  That  every  part  shall  be  easily  accessible  for  cleansing 
or  renewing  the  medium.  (2)  That  the  filtering  medium 
shall  have  sufficient  purifying  power  and  be  present  in 
sufficient  quantity.  (3)  That  the  medium  give  nothing  to 
the  water  favoring  the  growth  of  low  forms  of  life.   (4)  That 


Fig.  72. — Berkefeld  filter  attached  to  tap. 

the  purifying  power  be  reasonably  lasting.  (5)  That  there 
be  nothing  in  the  construction  of  the  filter  itself  capable 
of  undergoing  putrefaction  or  of  yielding  metallic  or  other 
impurities  to  the  water.  (6)  That  the  filtering  material 
shall  not  clog,  and  that  the  flow  of  water  be  reasonably 
rapid;  to  which  may  be  added:  (7)  That  the  filtering 
medium  be  such  that  it  can  be  readily  cleansed  and  ster- 
ilized, or  else  so  cheap  that  the  removal  and  replenishing 
may  not  be  neglected,  when  necessary,  on  account  of  the 
expense. 

House  filters  may  be  divided  into  three  classes:  (a) 


214 


WATER 


those  entirely  disconnected  from  the  water-supply  pipes 
of  the  house;  (b)  those  connected  with  the  water-pipes, 
but  intended  to  filter  only  a  limited  quantity,  as  for  drink- 
ing, cooking,  etc.;  (c)   those  connected  with  the  house 


Fig.  73. — Pasteur-Chamberland  filter  with  reservoir  for  filtered  water. 


service-pipe  and  intended  to  filter  all  the  water  used  in  the 
house.  The  same  filtering  media  may  be  used  in  all  three 
classes,  but  it  will  be  found  best  in  the  first  two  to  employ 
substances  through  which  the  water  passes  slowly,  while 
the  latter  class  must  necessarily  filter  the  water  more 


CLASSIFICATION  AND  CARE  OF  FILTERS      215 

rapidly  in  order  to  yield  a  sufficient  supply.    It  will  often 
be  advantageous  to  have  a  settling  tank  connected  with 


Fig.  74. — Glass  model  of  Loomis-Manning  filter,  showing  filter  in  action. 


those  of  the  first  class,  to  prolong  the  safe  use  of  the  filter 
as  long  as  possible;  while  the  same  object  is  gained  in  some 
of  the  second  class  by  bringing  the  water  in  at  the  bottom, 


216 


WATER 


in  which  case  there  should  be  a-  space  below  the  filtering 
medium  to  allow  the  suspended  matters  to  fall  away  from 


Fig.  75. 


-Glass  model  of  Loomis-Manning  filter,  showing  self-scouring 
of  material  during  cleansing. 


the  latter.    Those  intended  to  filter  the  whole  supply  of 
the  house  are  generally  cleansed  by  reversing  the  current 


TYPES  OF  FILTERS  217 

and  washing  the  collected  dirt  out  of  the  filter  into  a  drain 
or  sewer,  the  first  water  passing  through  the  filter  after 
this  is  done  being  also  discarded.  In  such  filters  the 
quantity  of  filtering  material  should  be  sufficient  to  purify 
thoroughly  the  water  passing  through  it,  and  yet  should 
not  be  so  heavy  that  the  reverse  or  washing  current  can- 
not lift  it  and  separate  the  particles  so  that  by  their  scour- 
ing action  upon  one  another  they  may  be  cleansed  and  all 
the  dirt  washed  out.  These  filters  also  may  be  so  ar- 
ranged that  a  small  quantity  of  a  coagulant,  such  as  alum, 
is  automatically  added  to  the  water  before  filtration.  If 
this  be  done,  care  must  be  had  to  supply  no  more  of  the 
coagulant  than  suitable  tests  show  to  be  necessary,  else 
the  excess  may  be  carried  through  the  filter  in  solution. 

No  matter  what  kind  of  filter  is  used,  the  drinking- 
water  should  always  be  boiled  in  times  of  epidemics  or 
when  the  water  before  filtration  is  especially  impure;  for, 
though  the  Berkefeld,  the  Pasteur-Chamberland,and  a  few 
other  filters  are  practically  bacteria-proof,  there  always 
remains  a  possibility  that  disease  germs  may  by  some 
means  pass  through  the  filtering  medium  or  gain  access 
to  the  water  after  it  is  filtered.  The  writer's  own  opinion 
is  that  there  is  a  saprophytic  or  biological  action  in  most 
good  filters  that  are  regularly  and  frequently  cleaned  very 
similar  to  that  which  takes  place  in  filter-beds  on  a  large 
scale,  and  that  ordinarily  few,  if  any,  bacteria  pass  through 
with  the  water;  but,  nevertheless,  the  risk  should  not  be 
taken  if  there  is  danger  of  incurring  disease  at  any  time. 

Filters  in  which  the  material  is  cemented  up  so  that  it 
cannot  be  removed  for  cleaning  or  renewal  should  not  be 
used.  Sponge,  wool,  etc.,  are  liable  to  decompose  and 
give  organic  matter  to  the  water  and,  moreover,  cannot  be 
thoroughly  cleaned.  Asbestos  acts  only  as  a  mechanical 
filter  and  may  allow  albuminous  matter  and  disease  germs 
to  pass.  Asbestos-cloth  may  be  used,  however,  to  support 
the  other  filtering  media  in  those  filters  where  the  water- 
supply  enters  at  the  bottom,  and  it  has  the  advantage 
that  it  can  be  perfectly  sterilized  by  fire.     Small  tap 


218 


WATER 


filters  are  insufficient  for  the  work  required  of  them  and 
soon  clog.    Pocket  filters  are  simply  strainers,  and  have 


-M 


Fig.  76. — Home-made  slow  sand  filter.  Capacity,  25  to  30  gallons 
per  twenty-four  hours  and  costs  about  $10.  A,  supply  pipe;  B,  brass 
tee,  plugged;  C,  brass  pet  cock;  D,  rubber  tube;  E,  concrete  cover;  F, 
concrete  slab  with  cone-shaped  hole  j2  inch  in  diameter  at  the  bottom 
of  the  slab  in  the  center;  G,  concrete  base  slab;  H,  J,  10-inch  vitrified 
pipe,  each  2  feet  long;  K,  water-tight  cement  fillet;  L,  overflow,  |-inch 
lead  pipe;  M,  §-inch  glass  tube;  A'',  J-inch  union;  O,  5-inch  vent  and 
overflow;  P,  tight  cap;  Q,  nut,  pipe  open;  R,  piece  of  slate,  brick  or 
tile;  S,  clean  fine  sand;  T,  1-inch  layer  of  coarse  sand;  U,  ^-inch  layer 
of  gravel  size  of  shot ;  V,  f-inch  layer  of  gravel  size  of  a  pea ;  W,  1  j-inch 
layer  of  gravel  about  5-inch  size;  X,  |-inch  brass  faucet  for  drawing 
filtered  water.  (Water  Systems  for  Farm  Homes,  U.  S.  Department 
of  Agriculture,  Farmers'  Bulletin,  p.  941.) 


MATERIALS  USED  AS  FILTERING  MEDIA     219 

little  oxidizing  power.  They  may  be  quite  useful  for 
tourists,  hunters,  etc.,  but  should  be  frequently  sterilized 
by  boiling.  Ordinarily,  filters  should  not  be  placed  in 
rain-water  cisterns,  but  outside,  where  they  may  be 
readily  cleaned. 

Among  the  best  filtering  media  are  sand,  animal  char- 
coal, magnetic  carbide  of  iron,  spongy  iron,  etc.  Unglazed 
porcelain  or  bisque,  as  is  used  in  the  Pasteur-Chamberland 
filter,  is  an  excellent  medium,  and  is  practically  germ- 
proof,  though  some  observers  state  that  bacteria  will  pass 
through  uncleaned  filters  of  this  material  after  five  or  six 
days  of  use.  Others  claim  that  these  are  not  bacteria,  but 
only  the  mycelia  of  certain  budding  fungi,  with  no  power  of 
reproduction,  and  the  former  statement  seems  to  have  been 
positively  disproved  with  respect  to  the  germs  of  typhoid 
fever,  colon  bacilli,  and  similar  organisms.  The  tubes 
of  the  Berkefeld  filter  are  made  of  diatomaceous  earth, 
molded  into  shape  by  powerful  hydraulic  pressure, 
so  that  the  water  percolates  through  the  pores  of  the 
minute  fossil  shells  rather  than  between  them.  If  kept 
clean,  these  give  good  service,  but  it  has  been  recently 
stated  that  typhoid  bacilli  will  pass  through  them  after 
several  days.  Stone  filters  may  be  good,  and  resemble 
the  porcelain  ones  in  action,  but  are  apt  to  be  slow  and 
must  be  cleaned  often.  Sharp,  clean  sand,  not  too  fine, 
has  fair  filtering  properties,  as  it  arrests  most  of  the  sus- 
pended matters  and  bacteria,  beside  oxidizing  somewhat 
the  dissolved  organic  matters.  It  makes  a  good  first  layer 
for  a  filter,  because  it  is  cheap  and  can  be  easily  renewed 
or  else  readily  cleansed  and  sterilized  by  boiling.  Crushed 
quartz  is  of  practically  the  same  nature. 

Animal  charcoal  is,  when  fresh,  an  excellent  material, 
as  it  removes  both  suspended  and  dissolved  matters, 
organic  and  inorganic,  and  even  color.  It  acts  both 
mechanically  and  chemically,  and  with  a  good  volume  of 
it  water  may  pass  through  rapidly  and  be  well  purified. 
But  after  a  time  it  ceases  to  be  effective;  nor  must  water 
be  left  too  long  in  contact  with  it,  as  it  will  give  up 


220  WATER 

organic  matter  to  the  water  again  and  also  calcium  phos- 
phate, the  latter  especially  favoring  the  development  of 
micro-organisms.  Moreover,  fresh  organic  matter,  and 
possibly  bacteria,  are  said  to  pass  through  it  readily, 
though  dead  or  decomposing  matter  is  retained  and 
rapidly  destroyed.  It  should  be  changed  or  cleansed, 
even  when  in  sufficient  bulk,  three  or  four  times  a  year; 
oftener  if  the  water  to  be  filtered  is  very  impure.  It  is 
more  efficacious  than  any  other  substance  in  removing 
lead  from  water. 

Magnetic  carbide  of  iron  is  one  of  the  best  filtering 
materials,  as  it  has  considerable  power  in  oxidizing 
organic  matters,  converting  them  into  nitrates  and  nitrites, 
the  action  being  greater  the  longer  the  water  is  in  contact 
with  it.  It  acts  partly  by  surface  condensation  of  oxygen ; 
partly,  perhaps,  by  electrolytic  action.  If  sand  be  used 
as  a  first  layer  to  remove  solid  matters  so  that  the  water 
reaches  the  carbide  perfectly  clear,  and  if  the  sand  be 
frequently  renewed  or  cleansed,  the  carbide  need  never 
be  changed;  but  the  filtration  must  be  intermittent  so 
that  the  carbide  may  be  frequently  aerated.  Spongy  iron 
has  an  action  very  similar  to  that  of  the  magnetic  carbide 
on  organic  matters,  and,  like  it,  the  action  is  the  greater 
the  longer  the  contact.  It  must  be  kept  covered  with 
water  to  prevent  rusting  and  caking,  and  should  be 
renewed  about  once  a  year.  The  small  amount  of  iron 
that  the  magnetic  carbide  and  spongy  iron  give  to  the 
water  may  be  removed  by  passing  it  through  a  layer 
of  pyrolusite — a  crude  magnesium  oxide.  A  mixture  of 
pyrolusite  and  sand  or  crushed  quartz  makes  an  excellent 
filtering  material. 

Regarding  house  filters,  the  following  caution  from  a 
Government  bulletin  is  worthy  of  notice.^  "A  filter  is  a 
device  for  removing  dirt  from  water.  It  promotes  purity 
and  safety,  but  never  is  a  guarantee.  It  does  not  excuse 
the  use  of  water  taken  from  sources  known  to  be  con- 

1  Farmers' "Bulletin,  No.  941,  U.  S.  Department  of  Agriculture;  Water 
Systems  for  Farm  Homes. 


MATERIALS  USED  AS  FILTERING  MEDIA      221 

taminated  Filtration  alone  does  not  materially  affect 
such  dissolved  matters  as  the  water  may  contain.  If, 
for  instance,  brine  be  filtered,  the  resultant  will  be  salt 
water.  Not  only  must  the  accumulated  dirt  be  removed 
from  filters  according  to  their  use  and  the  dirtiness  of 
the  water  filtered,  but  the  filtering  material  must  be 
cleaned,  aerated  or  sterilized  from  time  to  time.  Dirty 
.sand  can  be  washed,  but  dirty  charcoal  must  be  replaced 
with  new  charcoal  four  or  five  times  a  year.  Charcoal 
filters,  if  neglected,  may  become  a  detriment  rather  than 
a  benefit,  due  to  the  storage  and  overloading  of  organic 
matter  within  the  pores  and  upon  the  surface  of  the 
charcoal/' 

In  recent  years  other  methods  for  purifying  water, 
both  in  large  and  moderate  quantities  have  been  devised, 
the  various  agencies  employed  being  electricity,  ozone, 
ultra-violet  radiations,  etc.;  but  although  some  of  these 
methods,  at  least,  seem  fairly  well  perfected,  their  use 
is  still  somewhat  in  the  experimental  stage  and  not 
sufficiently  general  to  warrant  more  than  a  brief  mention 
in  a  work  of  this  kind. 

Ice  should  not  be  added  to  filtered  or  drinking-water, 
as  freezing,  even  for  a  long  time,  may  not  kill  certain 
disease  germs.  Prudden  has  kept  typhoid  bacilli  frozen 
in  ice  for  more  than  three  months  without  destroying 
their  power  of  growth  and  reproduction  when  brought  to 
a  suitable  temperature.  The  same  objections  do  not,  of 
*  course,  pertain  to  artificial  ice  carefully  made  from  dis- 
tilled water  as  to  that  from  polluted  ponds  or  rivers;  but 
it  is  well  to  cool  the  water  by  placing  it  in  stoppered 
bottles  upon  ice  or  in  vessels  surrounded  by  ice  rather 
than  by  adding  the  ice  to  the  water  directly. 

The  inadvisability  of  using  ice-water  freely  as  a  bev- 
erage should  be  mentioned  here,  as  the  habit  is  almost 
certain  to  cause  much  harm  to  the  digestive  apparatus, 
and  to  give  origin  not  only  to  intractable  dyspepsias,  but 
to  troubles  even  more  serious.  If  used  at  all,  ice-water 
should  be  taken  slowly  and  in  small  quantities,  and  as 


222  WATER 

little  as  possible  should  be  imbibed  at  meal-time,  in  order 
to  prevent  chilling  of  the  stomach  and  consequent  check- 
ing of  the  digestion.  Its  use  and  the  liking  for  it  are 
mainly  a  matter  of  habit  which  it  is  hygienic  wisdom  to 
overcome. 

EXAMINATION  OF  DRINKING-WATER. 

The  examination  of  a  drinking-water  should  have 
regard  to  its  physical,  bacterial,  and  chemical  properties 
as  well  as  to  a  consideration  of  all  the  conditions  affecting 
its  source,  storage,  and  distribution.  Consequently,  a 
decision  on  the  purity  of  water  should  be  governed  by 
all  the  available  know^ledge  of  the  circumstances:  whether 
it  is  well-water,  spring-water,  rain-water,  or  river- water; 
whether  it  has  been  at  any  time  exposed  to  pollution;  in 
what  kind  of  a  cistern  or  reservoir  it  has  been  stored,  etc. 

A  physical  examination  of  water  considers  the  color, 
clearness,  sediment,  lustre,  taste,  and  smell.  Pure  water 
has  a  bluish  tint,  but  most  waters  are  grayish,  greenish, 
yellow,  or  brown.  Yellow  or  brown  waters  are  subject  to 
suspicion,  as  the  color  may  be  due  to  animal  matter  or 
sewage,  though  vegetable  matters  or  iron  may  give  the 
same  color.  Green  waters  are  usually  harmless,  the  color 
being  due  to  vegetable  matters.  The  color  is  judged  by 
allowing  the  sediment  to  settle  and  then  siphoning  or 
pouring  off  the  supernatant  water  into  a  tall  glass  vessel 
or  tube  to  the  depth  of  about  twenty-four  inches;  the 
color  is  then  compared  with  that  of  a  similar  depth  of 
distilled  water,  looking  down  through  both  upon  a  white 
surface. 

The  clearness  of  a  water  is  to  be  estimated  in  the  same 
way,  except  that  the  sediment  is  to  be  shaken  up  with 
the  water.  The  depth  needed  to  obscure  print  of  a  cer- 
tain size  and  kind  of  type  may  be  used  as  an  index. 
Where  the  solid  matter  will  not  readily  settle,  owing  to 
the  minuteness  and  lightness  of  the  particles,  one  should 
determine  whether  the  use  of  a  coagulant  and  filtration  is 


EXAMINATION  OF  DRINKING-WATER         223 

indicated,  or  whether  boiHng  will  tend  to  precipitate  the 
sediment.  The  sediment  may  be  roughly  judged  by  the 
eye  as  to  whether  it  is  mineral  or  otherwise;  it  should  also 
be  examined  microscopically,  for  which  purpose  it  may  be 
collected  by  using  a  centrifugal  apparatus  or  by  allowing 
it  to  settle  from  the  water  in  a  conical  glass  and  then 
removing  it  to  the  slide  with  a  pipette.  Mineral  matters 
are  recognized  by  their  crystalline  or  amorphous  structure 
or  by  microchemical  tests;  vegetable  cells,  portions  of 
leaves,  etc.,  by  their  structure  and  the  presence  of  chlo- 
rophyll; animal  substances,  as  hair,  wool,  epithelial  and 
other  cells,  by  their  peculiar  characteristics.  Dark  brown, 
globular  masses  may  come  from  sewage.  Anything  indi- 
cating that  water  has  come  from  human  habitation  renders 
it  suspicious,  as  it  may  therefore  contain  sewage  or  other 
polluting  substances.  Some  of  the  larger  animalculse  and 
sometimes  iron  may  be  detected  with  the  naked  eye.^ 

The  lustre  is  supposed  to  indicate  the  amount  of  aera- 
tion; it  may  be  nil,  dull,  vitreous,  or  adamantine.  It 
should  not  be  forgotten  that  a  very  impure  water  may  be 
clear,  bright,  and  sparkling. 

Any  water  of  peculiar  or  unpleasant  taste  should  be 
considered  with  suspicion.  Dissolved  animal  matters 
may  be  tasteless,  but  suspended  substances  give  a  peculiar 
taste,  whether  animal  or  vegetal.  Iron  is  about  the  only 
ordinary  mineral  that  can  be  tasted  in  small  quantities. 
Good  water  depends  for  its  taste  mainly  upon  its  gases, 
and  water  free  from  gas  tastes  flat. 

The  smell  of  a  water,  if  it  has  any,  may  be  brought  out 
by  heating  gently  to  about  110°  F.,  or  by  boiling  it.  This 
may  make  evident  a  fecal  odoi;,  although  hydrogen  sul- 
phide may  mask  this  latter;  in  such  a  case  the  sulphide 
may  be  removed  by  adding  a  little  cupric  sulphate  to  the 
water.  The  odor  may  also  be  developed  by  allowing  the 
water  to  stand  in  a  stoppered  bottle  in  a  warm  place  for 
a  few  days. 

^  See  J.  C.  MacDonald's  Guide  to  Microscopic  Examination  of  Drink- 
ing-water. 


224 


WATER 


A  bacteriological  analysis  is  almost  as  necessary  as 
a  chemical  one,  for  purity  in  the  one  respect  does  not 
necessarily  indicate  purity  in  the  other.  The  presence  of 
Bacterium  coli  communis  in  a  water,  irrespective  of  any 
pathogenic  organisms,  would  create  more  than  a  suspicion 
of  contamination  by  fecal  matters,  as  this  microbe  is  prac- 
tically a  constant  occupant  of  the  human  intestinal  tract. 


'f  f  i^  ll,, 


Fig.  77. — Pocket-case  containing  sterilized  culture-tubes,  platinum  needle, 
and  alcohol  lamp,  used  for  obtaining  cultures  for  diagnosis,  etc. 

But  water  may  be  capable  of  carrying  typhoid  or  other 
infection  and  yet  be  free  from  colon  bacilli,  since  the 
disease  germs  may  have  been  introduced  into  the  water 
from  urine  rather  than  feces. 

Water  may  be  collected  for  bacteriological  analysis  in 
sterilized,  closed  bulbs  blown  from  glass  tubing.  The 
heat  used  in  sealing  the  ends  creates  a  partial  vacuum 


BACTERIOLOGICAL  ANALYSIS  225 

within  the  bulb,  so  that  if  the  tip  of  one  end  be  broken 
off  beneath  the  surface  of  the  water,  the  latter  is  drawn 
into  the  bulb,  which  can  then  be  resealed  and  conveyed 
to  the  laboratory.  But  as  some  of  the  bacteria  may  mul- 
tiply rapidly  in  transportation  and  as  some  species  may 
even  destroy  others,  it  is  always  best,  if  possible,  to  inocu- 
late the  tubes  of  sterilized  culture-media  at  the  place 
where  the  supply  for  examination  is  obtained.  Or  one 
may  add  a  small  quantity  of  the  water  to  melted  nutrient 
gelatin  at  the  time  when  the  samples  are  taken  and  make 
plate  cultures  in  the  manner  already  described.  The 
number  of  colonies  resulting  therefrom  will  indicate  prac- 
tically the  number  of  bacteria  in  the  volume  of  water 
added  to  the  gelatin. 

The  details  of  some  simple  but  fairly  accurate  tests  and 
methods  employed  in  the  chemical  analysis  of  drinking- 
water  will  be  given  in  another  chapter.  Here  we  need 
only  consider  the  influence  that  the  substances  sought  for 
in  the  analysis  have  in  affecting  potability,  and  within 
what  limits  we  may  consider  them  as  being  permissible 
in  drinking-water.  The  water  should  be  filtered  or  free 
from  sediment  for  all  the  tests,  except  in  the  estima- 
tion of  nitrogen  as  ammonia  compounds  and  as  organic 
matter,  and  of  the  oxygen-consuming  power  of  the 
water. 

The  amount  of  total  solids  will  vary  with  the  source  of 
the  water,  and  much  more  may  be  present  in  some  cases 
without  risk  of  harm  than  would  be  safe  in  others;  but 
usually  the  proportion  should  not  exceed  50  or  60  parts 
in  100,000.  Only  a  small  portion  should  be  volatile,  and 
there  should  be  little  charring  on  ignition,  except  in  the 
case  of  waters  from  peaty  soils;  nor  should  there  be  any 
odor  on  ignition,  especially  of  ammonia  compounds,  as 
that  would  indicate  an  excess  of  animal  organic  matter. 
Deep  well-water  will  probably  have  much  more  total 
solids  than  rain-water  or  clear  river-water,  the  excess 
being  mainly  mineral  substances  dissolved  from  the  strata 
through  which  the  water  passes. 
15 


226  WATER 

Even  the  purest  waters  contain  a  little  chlorine,  usually 
in  the  form  of  sodium  chloride;  but,  as  the  latter  is  a 
constant  constituent  of  household  slops  and  sewage  in 
general,  any  excess  of  chlorine  above  the  amount  common 
to  the  water  of  the  district,  unless  otherwise  accounted  for, 
will  be  decidedly  suspicious,  and  sewage  contamination 
should  be  looked  for.  So,  also,  any  sudden  increase  in 
the  proportion  of  chlorine  would  very  likely  indicate  the 
accession  of  some  new  source  of  contamination  to  the 
water.  Unless  accounted  for  by  the  strata  traversed  or 
by  the  locality,  more  than  3  parts  of  chlorine  in  100,000 
of  water  is  very  suspicious. 

The  presence  of  considerable  "free  ammonia"  in  rain- 
water is  not  a  bad  sign,  as  it  has  probably  been  absorbed 
from  the  air;  but  the  same  amount  in  subsoil-water,  espe- 
cially if  with  an  excess  of  chlorine,  would  indicate  prob- 
able contamination  with  urine,  as  the  latter  rapidly 
undergoes  ammoniacal  putrefaction.  In  such  a  case  there 
will  probably  also  be  considerable  "albuminoid  ammonia," 
but  much  albuminoid  ammonia  with  little  free  ammonia 
and  chlorine  generally  indicates  vegetable  contamination. 
The  writer  is  acquainted  with  a  case  in  which,  although 
the  water  is  pure  and  from  an  unpolluted  source,  the 
albuminoid  ammonia  and  chlorine  are  in  marked  excess, 
the  former  being  altogether  of  vegetable  origin — from  a 
peaty  soil — and  the  latter  characteristic  of  the  whole  dis- 
trict, which  is  near  the  sea-coast.  The  free  ammonia  is, 
however,  slight  in  amount.  An  excess  of  free  ammonia, 
chlorine,  nitrates,  and  nitrites  indicates  animal  contamina- 
tion, though,  if  the  pollution  be  by  effluvia  alone,  there 
may  be  no  excess  of  chlorine.^  The  total  ammonia  in 
a  usable  water  should  not  be  over  0.13  or  0.15  part  per 
1,000,000.  If  there  is  almost  no  "free"  ammonia,  the 
"albuminoid"  may  amount  to  0.1  part  per  1,000,000 
without  giving  cause  for  suspicion;  likewise,  if  there  is 
but  little  "albuminoid,"  there  may  be  considerable  "free" 
ammonia;  but   if  the   "albuminoid"   exceeds  0.05   part 

1  JCenwpod's  Hygienic  Laboratory,  p.  49, 


CHEMICAL  TESTS  227 

per  1,000,000,  the  "free"  must  not  be  greater  than  this 
proportion.  The  simplest  test  for  ammonia  is  by  means 
of  Nessler's  reagent — a  solution  of  a  double  iodide  of 
potassium  and  mercury.  It  gives  a  yellow  or  yellowish- 
brown  coloration  when  ammonia  is  present. 

Organic  matters  of  animal  origin,  and  therefore  nitro- 
genous, are  during  oxidation  partially  converted  into  am- 
monium compounds,  and  these,  by  the  action  of  certain 
bacteria,  may  be  further  oxidized  into  nitrites  and  nitrates. 
"  Nitrification  takes  place  under  the  influence  of  microbes, 
the  habitat  of  which  does  not  extend  more  than  a  few 
yards  below  the  surface  of  the  soil.  The  nitrifying  action 
is  probably  exerted  only  upon  the  ammonium  which  is 
formed  from  the  organic  matter.  The  presence  of  some 
substance  capable  of  neutralizing  acids  is  necessary  to 
continuous  action.  Calcium  and  magnesium  carbonates 
fulfil  this  function.  Nitrates  are  the  final  result  of  this 
action;  nitrites  are  present  at  any  given  time  only  in 
small  quantity."^  Deep  water  may,  of  course,  also  contain 
nitrates  taken  up  from  strata  rich  in  these  salts. 

Although  nitrites  and  nitrates  are  not  harmful  in  the 
quantities  usually  found  in  water,  and  though  the  water 
containing  them  may  have  been  thoroughly  purified  by 
natui*al  filtration  through  the  soil,  their  presence,  as  will 
be  seen  from  the  above  remarks,  is  important  in  deter- 
mining the  character  of  the  water.  The  presence  of  the 
slightest  trace  of  nitrites  is  always  suspicious,  and  any 
marked  amount  of  nitrates,  excepting  possibly  in  a  deep 
water,  should  require  close  investigation;  the  nitrates  and 
nitrites  together  measured  in  terms  of  nitrogen  should  not 
exceed  1  part  per  1,000,000. 

The  hardness  should  not  be  greater  than  that  indicated 
by  20  or  30  parts  of  chalk  in  100,000,  and  the  more 
"temporary"  in  proportion  to  the  "permanent"  hardness 
the  better. 

Phosphates,  not  from  phosphatic  strata,  help  to  indicate 

*  Leffmann  and  Bevan,  Examination  of  Water,  2d  edition,  p.  13. 


228 


WATER 


sewage  contamination.  So,  also,  do  sulphates,  though 
these  by  themselves  may  come  from  unimportant  sources. 

It  will  be  seen  from  the  above  statements  that  the 
opinion  regarding  any  water  must  be  based  on  a  broad 
consideration  of  all  the  circumstances  in  relation  to  it, 
and  not  from  the  presence  or  absence  in  it  of  any  one 
or  two  substances  which  are  not  in  themselves  harmful. 
The  presence  of  poisonous  metals  above  the  limits  of 
safety,  however,  would  alone  contra-indicate  the  use  of  a 
water.  For  instance,  there  should  not  be  more  than  0.04 
grain  of  lead  or  copper,  0.25  grain  of  zinc,  or  0.5  grain 
of  iron  to  the  gallon  in  any  water,  and  the  faintest  trace 
of  arsenic  condemns  it. 

The  following  table  has  been  adapted  from  Parkes: 

Classification  and  Properties  of  Various  Waters. 


Class. 


I. 

Pure  water. 


II. 

Usable 
water. 


III. 

Suspicious 
water. 


IV. 

Dangerous 
water. 


Physical. 


Colorless  or  bluish 
tint;  transparent, 
sparkling,  and  well 
aerated;  no  sedi- 
ment visible;  no 
smell;  taste  palat- 
able. 


Colorless  or  slight 
greenish  tint; 
transparent,  spark- 
ling, and  well  aer- 
ated; no  suspended 
matter,  or  easily 
separated  by  coarse 
filtration  or  sub- 
sidence; no  smell; 
taste  palatable. 

Yellow  or  strong 
green  color;  turbid; 
considerable  sus- 
pended matter;  no 
smell,  but  any 
marked  taste. 


Yellow  or  brown 
color;  turbid,  and 
not  easily  purified 
by  coarse  filtra- 
tion; large  amount 
of  suspended  mat- 
ter; any  marked 
smell  or  taste. 


Microscopic. 


Mineral  matter;  vege- 
table endochrome; 
large  animal  forms; 
no  organic  debris. 


Same    as    for    pure 
water. 


Vegetable  and  ani- 
mal forms,  more  or 
less  pale  or  color- 
less; organic  d6bris: 
fibers  of  clothing 
or  other  house  ref- 
use. 

Bacteria  of  any 
kind ;  fungi ;  nu- 
merous vegetable 
or  animal  forms  of 
low  types;  epithe- 
lia  or  other  animal 
structures;evidence 
of  sewage  or  ova  of 
parasites,  etc. 


Chemical 
(parts  per  100.000). 


Chlorine  under         1.4 
Total  solids  under  7.14 
Ammonia  under      0.007 
Nitrogen,  as  nitrites  and 
nitrates,   and  in   albu- 
minoid   ammonia, 
under  0.023 

Total  hardness        8.05 

Chlorine  under        4.3 
Total  solids  under  42.8 
Ammonia  under      0.015 
Nitrogen,  as  nitrites  and 
nitrates,  and   in   albu- 
minoid   ammonia, 
under  0.125 

Total  hardness      17.03 


Chlorine  4  to    7 

Total  solids  43  to  71 
Ammonia,  0.015  toO.023 
Nitrogen,  as  nitrites  and 

nitrates  0.124  to  0.237 
Total  hardness 

above  17.0 

Chlorine  above      7.14 
Total  solids  71.4 

Ammonia  above    0.0225 
Nitrogen,  as  nitrites  and 

nitrates,  above   0.242 
Total  hardness 

above  28.05 


CHAPTER  VI. 
FOOD. 

The  use  of  food  is  necessary  to  build  up  the  body- 
structure,  to  repair  waste,  and  to  furnish  force  and 
energy  for  the  proper  action  of  all  the  organs,  tissues, 
and  parts  of  the  body.  In  addition,  certain  substances 
are  needed,  not  so  much  because  they  become  a  part  of 
the  tissue  framework  or  yield  kinetic  energy  directly,  as 
that  they  are  essential  factors  in  the  multitudinous  chemi- 
cal reactions  and  changes  that  are  continually  occurring 
within  the  living  person.  We  may,  accordingly,  define 
a  food  as  anything  that  tends  to  fulfil  any  one  of  these 
functions,  provided  it  is  not  at  the  same  time  by  nature 
harmful  to  the  economy,  and  that  it  does  not  produce 
physiological  effects  out  of  proportion  to  its  nutritive  or 
metabolic  activities. 

Strictly  speaking,  this  definition  might  include  air  and 
water,  as  the  former  is  necessary  to  supply  oxygen  for 
union  with  other  foods  or  with  the  tissues  themselves, 
and  the  latter  is  needed  to  assist  in  the  solution  and 
assimilation  of  foodstuffs,  to  maintain  the  fluidity  of  the 
body-juices  and  to  moisten  the  tissues  effectively,  to  pre- 
serve roundness  of  form,  and  to  flush  out  and  remove 
from  the  system  those  waste  matters  and  excrementitious 
substances  whose  retention  gives  rise  to  the  symptoms  of 
certain  autogenetic  diseases.  But  they  are  not  usually 
included  in  the  category  of  foods,  and,  having  already 
been  considered,  they  may  be  passed  over  in  this  connec- 
tion with  but  incidental  reference  here  and  there. 

If  we  classify  foods  according  to  their  chemical  com- 
position, we  may  separate  them  into  the  following  main 
divisions:    (1)  Proteids   and  albuminoids;    (2)  Carbohy- 

(229) 


230  FOOD 

drates;  (3)  Hydrocarbons  or  fats;  and  (4)  Salts,  extrac- 
tives, etc.  Each  group  is  subject  to  different  digestive 
and  metabolic  processes,  and  each  has  usually  a  different 
office  within  the  body;  for  experience  and  careful  experi- 
ments both  show  that  all  of  these  different  food-principles 
are  needed  to  sustain  life  and  maintain  health  for  any  con- 
siderable length  of  time,  and  that  they  are  thus  the  chief 
essentials  of  food;  although  what  are  sometimes  called 
the  accessory  foodstuffs  and  many  pleasant  volatile 
odors  and  flavors  are  desirable  and  advisable  adjuncts 
to  the  food  proper,  since  they  greatly  favor  its  reception, 
digestion,  and  assimilation.  But,  though  each  class  of 
food  has  its  own  special  function  in  the  economy  of 
nutrition,  in  times  of  need  or  deprivation  any  one  of  the 
first  three  divisions  may,  in  a  way,  supply  the  place  of 
either  of  the  other  two. 

"Recently  it  has  been  suggested  that  beside  the  food- 
stuffs in  the  ordinary  sense,  other  constituents  of  our 
food  exist  which  are  of  the  very  greatest  importance  for 
life."^  To  this  latter  class  of  substances,  whose  lack 
seems  to  interfere  with  growth  and  to  cause  emaciation 
and  certain  diseases  the  term  vitamines  has  been  applied, 
although  it  must  be  said  that  the  term  is  not  well  chosen, 
as  they  are  not  members  of  the  amine  group  and  as  the 
above-mentioned  food  principles  are  equally  essential  to 
life. 

FothergilP  epitomizes  the  use  of  the  food-principles 
in  this  way:  "The  carbohydrates  are  the  body-fuel,  the 
surplusage  being  stored  as  fat;  the  albuminoids  (proteids) 
serve  to  repair  the  tissues  as  they  wear  out;  the  salts 
form  the  blood-salts;  the  fat  helps  to  build  up  normal 
health  tissues,  the  excess  being  burnt  as  body-fuel.  That 
is  the  real  object  of  food." 

While  in  the  main  correct,  this  is  a  broad  statement 
of  facts,  and  it  needs  qualification.     For  instance,  just 

^  Text-book  on  Physiological  Chemistry,  Hammarsten  and  Hedin- 
Mandel,  1905,  7th  ed. 

2  Manual  of  Dietetics,  p.  5. 


FOOD  PRINCIPLES  231 

as  there  is  some  wear  and  tear  in  any  mechanical  machine 
while  in  use,  which  must  eventually  be  provided  for, 
so  in  the  human  body  with  its  manifold  activities,  there 
must  be  some  destructive  effect  upon  the  body-structure 
and  tissue  framework,  and  it  is  to  renew  and  replace 
this  inevitable  loss  of  material  that  a  part — perhaps  the 
larger  or  greater  part — of  the  proteid  food  is  taken. 
But  we  also  know  that  in  addition  to  this  simple  repair 
and  replacement  of  tissue,  "the  presence  of  nitrogenized 
structure,  and  its  participation  in  the  action  going  on 
there,  is  a  necessary  condition  for  the  manifestation  of 
any  vital  energy  or  any  chemical  change,"  and  we  have 
reason  to  believe  that,  entirely  apart  from  the  idea  of 
repair,  proteid  food  is  essential  to  the  development  and 
maintenance  of  this  chemical  and  vital  activity  of  nitro- 
genized tissue. 

Confirming  this,  Pettenkofer  and  Voigt  have  shown 
that  the  absorption  of  oxygen  is  largely  determined  by 
the  nitrogenous  substances  composing  the  tissues  of  the 
body,  and  that  it  is  proportional  to  their  size  and  vigor. 
Moreover,  it  is  known  that  proteids  may  be,  in  part, 
converted  into  fat  and  possibly  into  other  oxidizable 
substances,  and  thus  become  a  source  of  body-heat  and 
energy. 

So,  also,  with  the  fats  and  carbohydrates.  While  they 
are  not  immediately  nor  entirely  interconvertible,  and 
while  neither  class  may  be  permanently  excluded  from 
the  diet,  yet  in  emergency  either  may  apparently  fully 
supplant  and  substitute  the  other  for  a  time,  and  we  can- 
not yet  say  exactly  how  similar  or  dissimilar  their  service 
within  the  body  is. 

However,  while  Fothergill's  epitome  needs  this  emen- 
dation, known  facts  make  it  comparatively  easy  to  gain 
a  fair  idea  of  the  differences  and  functions  of  the  proxi- 
mate food-principles,  to  which  end  some  help  will  probably 
be  given  by  the  following  table:* 

*  Notter  and  Firth,  Treatise  on  Hygiene,  p.  257. 


Properties  and  Functions  of  Food-principles. 


Nitrogenous  Substances. 
1.  Proteids. 

All  substances  containing  nitro- 
gen of  a  composition  identical 
with  or  nearly  that  of  albumin; 
proportion  of  N  to  C  being  nearly 
as  2  to  7  or  4  to  14. 


1  (a)  Substances  containing  a 
larger  proportion  of  nitrogen  are 
apparently  less  nutritious. 

Proportion  of  N  to  C  about  2  to 
5^  or  4  to  11. 

1  (6)  Extractive  matters,  such  as 
are  contained  in  the  juice  of  the 
flesh. 


Non-nitrogenous  Substances. 
2.  Fats  (or  Hydrocarbons) . 

Substances  containing  no  nitrogen, 
but  made  up  of  carbon,  hydro- 
gen, and  oxygen;  the  proportion 
of  oxygen  being  less  than  suffi- 
cient to  convert  all  the  hydrogen 
into  water. 

Proportion  of  unoxidized  H  to  C, 
about  1  to  7. 

3.  Carbohydrates. 

Substances  containing  no  nitrogen, 
but  made  up  of  carbon,  hydrogen, 
and  oxygen;  the  oxygen  being 
exactly  sufficient  to  convert  all 
the  hydrogen  into  water. 

Proportion    of    water    to    carbon, 
about  3  to  2. 
3  (a)     Vegetable  acids  {and  pectous 
substances) . 

Substances  containing  no  nitrogen, 
but  made  up  of  carbon,  hydro- 
gen, and  oxygen;  the  oxygen  be- 
ing generally  in  greater  amount 
than  is  sufficient  to  convert  all 
the  hydrogen  into  water. 


4.   Salts  (mineral). 


Examples. 


Animal: 
Albumin, 
Fibrin, 
Syntonin, 
Myosin, 
Globulin, 
Casein. 

Vegetable: 
Glutin, 
Legumin. 


Gelatin, 
Ossein, 
Chondrin, 
Keratin, 


Olein, 

Stearin, 

Margarin, 


Starch, 

Dextrin, 

Cane-sugar, 

Grape-sugar 

Lactin      (or 

milk-sugar) 

(More        O 
than  is  suf- 
ficient    to 
convert  all 
H  into  H2 
O.) 
Oxalic  acid. 
Tartaric   " 
Citric        " 
Malic        " 
(No     excess 

of  O.) 
Acetic  acid, 
Lactic     " 

Sodium 

chloride, 
Potassium 

chloride, 
Calcium 

phosphate. 
Magnesium 

phosphate, 
Iron,  etc. 


Functions. 


Formation  and  repair  of  tissues 
and  fluids  of  the  body. 

Regulation  of  the  absorption 
and  utilization  of  oxygen. 
May  also  form  fat  and  yield 
energy  under  special  condi- 
tions. In  most  foods  the 
above,  both  animal  and  vege- 
table, are  largely  converted 
into  albumoses  and  peptones. 

These  perform  the  above  func- 
tions less  perfectly,  or  only 
under  particular  circum- 
stances. 

These  substances  appear  es- 
sential as^regulators  of  diges- 
tion and  assimilation,  espe- 
cially with  reference  to  the 
gelatin  group. 


Supply  of  fatty  tissues;  nutri- 
tion of  nervous  system;  sup- 
ply of  energy  and  animal  heat 
by  oxidation. 


Production  of  energy  and  ani- 
mal heat  by  oxidation;  form 
fats  and  possibly  some  proteid. 


Preserve  the  alkalinity  of  the 
blood  by  their  conversion  into 
carbonates;  furnish  a  small 
amount  of  energy  or  animal 
heat  by  oxidation. 


Various ;  support  of  bony  skele- 
ton, supply  of  HCl  for  diges- 
tion, etc.  Regulators  of  en- 
ergy and  nutrition. 


DIETETICS—PHYSIOLOGY  OF  DIGESTION      233 

DIETETICS. 

Dietetics  means  "the  branch  of  medicine  or  hygiene 
that  treats  of  diet  and  dieting,"  and  its  study  includes  "a 
systematic  regulation  of  the  diet  for  hygienic  or  thera- 
peutic purposes."  It  considers  all  the  factors  that  affect 
the  proper  digestion  and  assimilation  of  food.  For 
instance,  it  is  not  alone  necessary  to  determine  just  what 
substances,  in  a  chemical  sense,  the  body  needs  to  sustain 
life  and  maintain  health.  Nor  is  it  sufficient  to  say 
that  a  man  must  have  just  so  much  of  this  and  so  much 
of  that  food,  for  there  must  always  be  a  variation  in 
both  kind  and  quantity  to  meet  the  changing  demands  of 
the  system.  With  a  few  exceptions,  no  matter  how  tooth- 
some or  healthful  a  certain  food  may  be,  it  soon  palls  upon 
the  appetite  if  necessity  compels  its  continued  use  for  a 
prolonged  period,  and  this  disgust  may  be  so  impressed 
upon  the  memory  of  the  senses  as  to  cause  them  to  object 
to  the  use  of  that  food  forever  after. 

The  esthetic  factors  in  the  preparation  and  serving  of 
food  must  also  be  taken  into  account,  and  the  success 
in  pleasing  the  taste  and  appetite  has  much  to  do  with  the 
progress  and  completeness  of  digestion.  Other  things 
being  equal,  palatable  and  agreeable  foods  are  disposed  of 
much  more  satisfactorily  than  others  not  so,  and  physi- 
cians and  others  should  learn  that  especially  in  sickness 
the  appearance  and  palatability  of  a  food  have  much  to 
do  with  its  acceptance,  not  only  by  the  patient,  but  by 
his  stomach  as  well.  Cleanliness  and  neatness  of  food, 
china,  and  napery  are  of  greater  value  than  expense  or 
show,  and  a  little  attention  and  tact  in  such  matters  will 
often  enable  a  patient  to  take,  enjoy  and  retain  food  and 
receive  nourishment,  even  when  he  or  she  asserts  and 
believes  this  to  be  impossible. 

Another  factor  of  much  importance  in  the  digestion  of 
food,  but  one  too  often  too  lightly  considered,  is  the  mood 
or  state  of  mind  when  the  food  is  taken  and  while  it 
remains  in  the  alimentary  canal.     There  is  more  than 


234  FOOD 

moral  philosophy  in  maintaining  a  cheerful  and  a  tran- 
quil disposition  during  the  daily  meals  and  for  a  time 
thereafter;  while  there  are  numerous  instances  of  most 
serious  results  occurring  from  the  giving  way  to  anger  or 
other  intense  emotion  at  such  times,  the  digestive  func- 
tions being  either  completely  checked,  or,  what  is  fre- 
quently worse,  so  altered  that  their  products  are  toxic  in 
character.  And  is  not  a  dyspeptic  often  so  because  of 
his  pessimism,  rather  than  a  misanthrope  because  of  his 
indigestion? 

Before  proceeding  further  it  will  be  well  to  consider 
briefly  the  physiology  of  digestion  in  so  far  as  it  concerns 
the  chemical  changes  occurring  in  the  food  while  it  is  in 
the  digestive  tract.  These  changes  are  brought  about  by 
the  action  of  certain  bodies  secreted  or  elaborated  by  the 
digestive  organs  and  glands,-  which  we  have  been  in  the 
habit  of  calling  unorganized  ferments,  but  which  would, 
perhaps,  better  be  known  hereafter  as  enzymes.  Unor- 
ganized ferments  are  so  called  because  they  have  not  the 
definite  cell-formation,  life,  and  power  of  reproduction 
which  belong  to  the  yeasts,  mould-fungi,  and  bacteria 
which  bring  about  the  fermentative  changes  in  organic 
substances  so  commonly  within  the  knowledge  of  everyone, 
such  as  the  conversion  of  saccharine  solutions  into  alcohol, 
of  alcohol  into  acetic  acid,  etc. 

But  though  unorganized,  the  enzymes  likewise  act  upon 
organic  matter;  for  example,  upon  the  food  which  we  eat, 
and — like  the  other  ferments — they  apparently  do  this 
simply  by  their  presence  rather  than  by  entering  into 
actual  combination  with  the  matter  acted  upon,  as  do  ordi- 
nary chemical  reagents.  They  are  undoubtedly  the  prod- 
ucts of  glandular  protoplasm,  probably  proteid  in  nature, 
and  some,  at  least,  very  likely  belonging  to  the  group  of 
nucleo-albumins,  which  latter  form  a  component  part  of 
every  organic  cell. 

The  comprehension  of  the  digestive  functions  will  be 
greatly  simplified  if  the  student  remembers  that,  "  with  the 
possible  exception  of  the  coagulating  enzymes,  the  action 


DIGESTIVE  FERMENTS  OR  ENZYMES  235 

of  the  enzymes  is  that  of  hydrating  agents:  they  produce 
their  effect  by  what  is  known  as  hydrolysis — that  is,  they 
cause  the  molecules  of  the  substance  upon  which  they  act 
to  take  up  one  or  more  molecules  of  water;  the  resulting 
molecule  then  splits  or  is  dissociated,  with  the  formation 
of  two  or  more  simpler  bodies."^ 

Thus  the  insoluble  proteids  and  carbohydrates  become 
respectively  the  soluble  amino-acids  and  sugars  of  their 
allies,  capable  of  being  absorbed  into  the  myriad  capillaries 
that  are  distributed  throughout  the  lining  membrane  of  the 
alimentary  tract.  Even  the  change  that  takes  place  in  fat 
when  digested  is  one  that  involves  the  taking  up  of  some 
water. 

There  are  four  characteristics  of  the  enzymes  worthy  of 
note:  (1)  That  they  are  all  soluble  in  water  and  glycerin, 
the  latter  being  especially  useful  in  making  stable  prepara- 
tions of  them  from  the  organs  producing  them.  (2)  "  That 
very  low  temperatures  (0°  C.)  retard  or  suspend  entirely 
their  action,  without,  however,  destroying  the  enzyme; 
that  for  each  enzyme  there  is  a  temperature  at  which  its 
action  is  greater,"  and  that  "in  a  moist  condition  they 
are  all  destroyed  by  temperatures  below  the  boiling-point; 
60°  to  80°  C.  are  the  limits  actually  observed."^  (3)  "  That 
they  never  completely  destroy  the  substance  upon  which 
they  act,"  probably  being  retarded  by  their  products  when 
the  latter  reach  a  certain  percentage.  "When  these  are 
removed,  the  action  of  the  enzymes  begins  again."  4. 
"Except  for  very  small  quantities,  it  may  be  said  that 
the  amount  of  change  caused  is  independent  of  the  amount 
of  enzyme  present;"  or,  rather,  "with  increasing  amounts 
of  enzymes  the  extent  of  action  also  increases,  reaching  a 
maximum  with  a  certain  percentage  of  enzyme;  increase 
of  enzyme  beyond  this  has  no  effect."  The  amount  of 
work  capable  of  being  done  by  a  small  proportion  of  an 
enzyme  is  enormous,  good  pepsin,  for  instance,  having  the 


*  American  Text-book  of  Physiology,  Ist  edition,  p.  219. 
2  Ibid. 


236  FOOD 

power  of  converting  2500  times  its  own  weight  of  proteid; 
but  we  must  remember  that  this  power  is  not  infinite,  and 
that  after  a  time  the  enzymes  will  cease  to  act. 

There  are  five  groups  or  classes  of  enzymes  concerned 
with  the  proper  digestion  of  food  to  be  found  in  the  ani- 
mal body,  and  it  is  interesting  to  note  that  examples  of 
each  of  these  classes  are  also  to  be  found  in  various  mem- 
bers of  the  vegetable  world.  The  two  principal  remaining 
classes,  being  neither  of  animal  origin  nor  digestive  agents, 
need  only  be  mentioned  here :  they  are  the  glucosidS-split- 
ting  and  urea-splitting  enzymes,  the  latter  being  produced 
by  certain  bacteria  and  converting  urea  into  ammonium 
carbonate. 

Considering  the  digestive  processes  in  their  order  as  the 
food  proceeds  from  the  mouth  through  the  alimentary 
canal,  we  find  that  the  first  active  secretion  or  fluid 
is  the  saliva,  and  that  its  enzyme  is  ptyalin,  belonging 
to  that  group  which  converts  the  insoluble  carbohydrates 
(starches)  into  soluble  sugars,  maltose,  etc.  Ptyalin  acts 
best  in  neutral  or  slightly  alkaline  media,  at  about  the 
body-temperature  (40°  C),  and  upon  cooked  much  better 
than  upon  raw  starch.^  Its  action  is  retarded  or  totally 
checked  by  a  low  temperature  or  by  strongly  alkaline  or 
moderately  acid  solutions,  and  the  enzyme  itself  is  prob- 
ably destroyed  by  an  increase  in  acidity  equal  to  that  of 
the  gastric  juice,  or  by  a  temperature  of  65°  or  70°  C.  The 
reason  it  converts  cooked  starch  so  much  more  quickly 
is  probably  because  the  heating  process  breaks  up  the 
cellulose  envelopes  upon  which  the  ptyalin  has  almost 
no  effect  and  which  protect  the  starch  granules  within 
from  its  action.    The  heat  also  causes  a  very  close  union 

^  Kubel  claims  to  have  found  that  an  alkaline  reaction,  even  when 
very  weak,  actually  interferes  with  ptyalin  digestion,  but  that  it  is 
favored  by  a  weak  acid  reaction,  especially  if  the  acid  be  one  of  the 
stronger  ones  like  HCl.  He  admits  that  an  amount  of  hydrochloric 
acid  equivalent  to  that  of  the  gastric  juice  checks  the  activity  of  the 
ptyalin,  but  believes  that  at  the  beginning  of  a  meal  and  for  a  time 
thereafter  salivary  digestion  takes  place  better  in  the  stomach  than  in 
the  mouth.     (Boston  Medical  and  Surgical  Journal,  April,  1899.) 


ACTION  OF  ENZYMES  237 

between  the  molecules  of  starch  and  water,  this  facilitating 
the  later  hydrolysis  by  the  enzyme. 

In  addition  to  its  digestive  function,  the  saliva  also 
serves  to  moisten  dry  food  so  that  it  may  be  swallowed, 
and  to  dissolve  sapid  and  savory  substances  that  they  may 
be  duly  appreciated  by  the  organs  of  taste. 

Our  first  hygienic  lesson  in  regard  to  the  digestive 
functions  is,  therefore,  that  in  order  to  get  the  full  benefit 
of  the  salivary  secretions,  all  food,  and  especially  that  of 
a  starchy  nature,  should  be  well  masticated  and  retained 
in  the  mouth  for  some  little  time,  instead  of  its  being 
"bolted"  at  once  or  after  a  hasty  bite  or  two.  Evidence 
is  also  at  hand  that  with  proper  mastication  there  will  be 
little  danger  of  overeating,  and,  in  most  cases,  a  decided 
decrease  in  the  consumption  of  proteids,  the  latter  prob- 
ably resulting  in  a  lessening  of  fatigue  products  and  an 
increase  in  endurance. 

Nor  should  very  cold  or  very  hot  beverages  be  taken  at 
the  same  time  with  food,  for  not  only  will  the  action  of 
the  ptyalin  be  thus  retarded  or  destroyed,  but  that  also, 
as  we  shall  see,  of  the  gastric  juice  within  the  stomach. 
A  note  here  as  to  the  drinking  of  water  at  meal-time  will 
not  be  out  of  place.  A  moderate  quantity  of  proper  tem- 
perature will  probably  be  beneficial  rather  than  otherwise, 
since  it  helps  in  the  solution  of  the  food;  but  an  exces- 
sive quantity  tends  to  harm  by  diluting  the  enzymes 
too  much,  thus  interfering  with  their  reactions,  and  by 
interfering  with  the  absorption  of  the  digested  matters. 
Moreover,  it  has  been  shown  that  not  only  does  the  saliva 
act  best  when  diluted  with  about  three  times  its  volume 
of  water  and  provided  the  food  has  been  thoroughly  mas- 
ticated, but  also  that  water  is  a  positive  excitant  of  both 
the  gastric  and  pancreatic  secretions.^ 

The  food,  having  passed  from  the  mouth  to  the  stomach, 
may  still  be  acted  upon  for  a  time  by  the  ptyalin  until 
the  work  of  the  latter  is  checked  by  the  acid  of  the  gastric 

^  See  Physiology  of  Alimentation,  Martin  H.  Fischer,  pp.  104,  226, 
and  232. 


238  FOOD 

juice. ^  The  energy  of  digestive  action  is  then  transferred 
from  the  starches  to  the  proteid  constituents  of  the  food, 
the  chief  enzyme  now  being  pepsin,  though  we  also  find 
in  the  gastric  juice  a  coagulating  ferment — rennin — which 
acts  upon  soluble  proteids,  like  the  casein  of  milk,  to 
form  clots  or  curds. 

Pepsin  acts  only  in  an  acid  medium  (the  acidity  being 
supplied  normally  by  the  free  hydrochloric  acid  of  the 
gastric  juice),  and  best  at  the  body-temperature.  As 
stated,  extremes  of  temperature  are  adverse  to  its  activity 
and  may  check  it  altogether,  and,  likewise,  too  much  or 
too  little  acid  may  have  the  same  effect,  from  0.2  to  0.3 
per  cent,  of  HCl  being  the  normal  amount  and  giving  the 
best  results.  Rennin^  seems  in  the  normal  stomach  to  act 
only  on  the  casein  of  milk,  and  curdles  this  probably 
because  it  is  then  more  easily  digested  by  the  pepsin  and, 
later,  by  the  trypsin  of  the  pancreatic  juice. 

The  action  of  the  pepsin,  plus  the  acid,  upon  the  proteids 
of  the  food  is  a  hydrolytic  one,  and  the  end-products  are 
practically  hydrated  proteids,  called  albumoses  and  pep- 
tones. The  gastric  digestion,  therefore,  after  the  action 
of  the  ptyalin  has  been  checked  by  the  acid  gastric  juice, 
practically  has  to  do  only  with  the  albuminous  or  nitrog- 
enous part  of  the  food,  the  remainder,  or  at  least  that  part 
of  it  not  yet  capable  of  absorption,  remaining  unchanged 

^Recent  experiments  seem  to  show  that  "ptyalin  digestion  normally 
continues  during  the  first  hour  of  gastric  digestion,  or,  in  fact,  until  the 
hydrochloric  acid  secretion  reaches  the  normal  maximum."  (A.  L. 
Benedict,  Journal  of  the  American  Medical  Association,  July  28,  1900.) 
Griitzmer  has  also  shown  (Pfluger's  Archiv,  1905,  cvi,  436)  that  the  reac- 
tion within  the  main  mass  of  the  food  in  the  stomach  may  remain  alka- 
line or  neutral  for  some  two  hours,  the  digestion  of  proteids  by  pepsin 
going  on  only  at  the  pyloric  end  and  in  that  part  of  the  food  that  is  in 
contact  with  the  stomach  walls. 

2  Oppenheimer  says  concerning  rennin:  "It  does  not  appear  to  have 
any  essential  significance  for  the  digestion  of  proteids.  It  is  strikingly 
absent  in  the  newborn,  who  consume  much  milk.  Zuntz  and  Sternberg 
have  even  found  that  milk  proteid  coagulated  by  rennin  is  less  easily 
digested  than  the  original  milk  proteid,  and  attributed  to  this  in  part 
the  relatively  smaller  availability  of  milk  for  adults,  who  produce  more 
rennin."  (Torald  Sollmann,  Journal  of  the  American  Medical  Associa- 
tion, February  9,  1907,  p.  521.) 


INTESTINAL  DIGESTION  AND  ABSORPTION     239 

until  it  passes  further  on  into  the  intestines.  Soluble 
salts,  sugars,  and  part  at  least  of  the  peptones  as  they 
are  formed,  may,  however,  be  taken  up  by  the  stomach 
capillaries,  while  the  rest  of  the  food-mass,  kept  ever 
in  motion  by  the  muscular  movements  of  the  stomach- 
walls,  is  being  thoroughly  mixed  and  converted  by  the 
peptic  action  into  the  semiliquid  substance  called  chyme, 
which  is  passed  at  intervals  and  in  small  quantities  through 
the  pyloric  opening  into  the  duodenum. 

Long  before  the  stomach  has  entirely  emptied  itself — 
which  may  only  be  after  several  hours  of  activity^ — intes- 
tinal digestion  is  well  under  way,  and  in  some  respects  this 
is  the  most  important  as  well  as  the  most  comprehensive 
process  of  all.  The  three  secretions  to  whose  combined 
action  the  chyme  is  now  subject  are  the  pancreatic  juice, 
the  bile,  and  the  intestinal  juice.  All  are  alkaline  and 
quickly  neutralize  the  gastric  acid;  it  scarcely  need  be 
noted,  then,  that  the  remaining  enzymes  act  best  or  only 
in  alkaline  media,  though  one  of  them,  trypsin,  may  act 
in  solutions  not  too  strongly  acid. 

In  the  pancreatic  juice  we  find  three  enzymes,  prac- 
tically the  only  remaining  ones  of  much  importance; 
although  in  the  rather  scanty  intestinal  juice  two  others 
have  been  found,  one  capable  of  converting  starch  into 
sugar  and  the  other  of  inverting  cane-sugar  into  levulose 
and  dextrose.  The  bile  contains  no  enzymes.  The  pan- 
creatic ferments  are  trypsin,  which  acts  upon  proteids 
and  albuminoids  even  more  powerfully  than  pepsin,  and 
which  also  converts  the  resultant  albumoses  and  peptones 
into  amino-acids,  the  end  products  of  proteid  digestion; 
amylopsin,  which  is  practically  identical  with  ptyalin  in 
its  function;  and  steapsin,  which  causes  neutral  fats  to 
take  up  water  and  split  into  free  fatty  acids  and  glycerin. 

1  "Cannon  and  others  have  shown  that  the  main  mass  of  the  food 
remains  in  the  stomach  for  a  considerable  time — three  hours  with  a 
carbohydrate  meal,  six  hours  with  a  proteid  meal,  twenty-one  hours  with 
a  fatty  meal.  A  portion  of  the  food  leaves  the  stomach  much  earlier." 
(Torald  Sollmann,  loc.  cit.,  p.  522.) 


240  FOOD 

Under  the  action  of  the  trypsin,  aided  by  erepsin, 
another  ferment  secreted  by  the  intestine,  all  that  portion 
of  the  proteid  food  which  has  not  been  completely  digested 
in  the  stomach  reaches  that  stage  in  the  small  intestine 
and  is  absorbed  therefrom.  In  fact,  it  is  very  probable 
that  the  tryptic  digestion  is  often  the  more  important  of 
the  two.  As  the  action  of  the  saliva  upon  the  carbohy- 
drates, which  form  the  greater  bulk  of  our  food,  must  of 
necessity  be  comparatively  limited,  it  is  evident  that 
most  of  the  starch  digestion  is  performed  by  the  amylopsin, 
aided  in  slight  measure  by  the  similar  enzyme  of  the  intes- 
tinal juice.  The  salts  and  other  soluble  elements  of  the 
food  having  already  been  absorbed,  there  remain  only  the 
fats  or  hydrocarbons  to  be  considered. 

Under  the  influence  of  the  steapsin  a  comparatively 
small  portion  of  the  fat  in  the  food  is  separated  into 
glycerin  and  free  fatty  acids,  arid  this  action  for  some 
reason  takes  place  much  more  rapidly  when  aided  by  the 
bile  than  with  the  pancreatic  juice  alone.  Then  these 
fatty  acids  unite  with  the  alkalies  and  alkaline  salts  of 
the  above  secretions,  but  especially  of  the  bile  and  intes- 
tinal juice,  to  form  soaps,  and  these  soaps  aid  the  steapsin 
in  emulsifying  the  remainder  of  the  fats  and  in  thus  making 
them  ready  for  absorption,  which  latter  process  is  also 
facilitated  by  the  direct  action  of  the  bile  upon  the 
intestinal  epithelium. 

The  student  must  not  get  the  idea  that  the  absorption 
of  digested  food  from  the  alimentary  canal  is  merely  a 
physical  process  and  a  simple  matter  of  osmosis  or  dif- 
fusion. Accumulating  experience  indicates  that  it  is  in 
a  measure,  if  not  largely,  vital  and  physiological,  and  that 
"the  living  cells  of  the  intestinal  wall  appear  to  take  an 
active  share  in  the  process,  and  modify  the  action  of  the 
physical  factors  in  a  manner  not  at  present  understood." 
This  is  probably  especially  true  as  regards  the  absorption 
of  the  fats,  whether  we  take  the  commonly  accepted  view 
that  most  of  the  fat  is  emulsified  and  only  a  small  portion 
split  up  and  saponified  in  the  intestine,  or  the  one  which 


IMPORTANCE  OF  DIETETIC  HABITS  241 

some  have  advocated  of  late  years,  viz.,  that  almost,  if 
not  all,  of  the  fat  is  decomposed  and  dissociated,  and 
comparatively  little,  if  any,  emulsified. 

The  digestive  processes  having  thus  been  outlined,  it 
will  be  well  to  learn  how  they  may  be  maintained  as 
complete  and  perfect  as  possible.  In  the  first  place,  the 
cooking  of  food  is  usually  an  essential  preliminary.  We 
cook  meats  not  only  to  make  them  more  agreeable  to 
the  palate,  but  also  to  facilitate  digestion.  The  efi^ect  of 
cooking  upon  muscle  (flesh)  is  "to  loosen  the  bundles  of 
fibrillse  from  each  other,  so  that  they  are  readily  torn 
asunder  or  crushed  by  the  teeth,"  while  the  various  con- 
nective tissues  are  softened  and  gelatinized,  not  only  thus 
becoming  more  digestible  and  nutritious,  but  also  allowing 
the  histological  elements  which  they  bind  together  to  sepa- 
rate and  be  more  freely  acted  upon  by  the  solvent  fluids. 
So  with  the  vegetables,  the  heat  and  steam  soften  and 
rupture  the  cellulose  envelopes  of  the  various  cells  that  the 
ferments  may  the  more  readily  act  upon  their  contents; 
and  at  the  same  time  they  bring  about  subtle  chemical 
changes  that  greatly  increase  the  palatability  of  the  food- 
stuffs. 

Thorough  mastication  of  the  food  is  important  for  the 
reasons  already  stated,  and  the  cause  of  most  dyspepsias 
may  be  found  in  faulty  habits  of  eating.  Foster  says 
that  in  the  stomach  "the  natural  bundles  of  meat  and 
vegetables  fall  asunder,  the  muscular  fibres  split  up  into 
disks,  and  the  protoplasm  is  dissolved  from  the  vegetable 
cell;"  but,  "if  the  meat  be  not  chewed  properly,  but 
'bolted,'  the  solvent  gastric  juice  can  only  act  on  the 
exterior  of  the  mass,  while  'lumps'  offend  the  stomach 
and  arrest  the  gastric  secretion."  "Coarse  particles  of 
food  also  delay  the  opening  of  the  pylorus,  and  so  keep 
a  meal  in  the  stomach  a  correspondingly  longer  time."* 
The  importance  of  abstaining  at  meal-time  from  beverages 
or  other  substances  of  too  low  or  too  high  a  temperature 

1  Physiology  of  Alimentation,  Fischer,  p.  14. 
16 


242  FOOD 

has  already  been  noted,  and,  as  all  the  enzymes  act  best 
at  the  body-temperature,  care  should  always  be  had  to 
avoid  chilling  of  the  abdominal  organs  while  digestion  is 
under  way. 

Again,  as  the  formation  and  action  of  the  enzymes 
begin  with  the  ingestion  of  food  and  depend  largely  upon 
a  sufficient  blood-supply  to  the  organs  concerned  as  long 
as  digestion  continues,  it  is  essential  that  the  blood-current 
shall  not  be  diverted  from  these  organs  during  this  period 
by  excessive  mental  or  physical  demands,  and  that  a  con- 
dition of  cheerfulness,  repose,  and  rest  should  prevail 
during  and  following  every  meal.  Regularity  as  to  the 
time  of  meals  and  the  avoidance  of  too  great  a  tax  upon 
any  of  the  organs  by  overindulgence  or  intemperance  in 
eating  are  likewise  both  important  matters  and  ones  too 
often  neglected. 

It  is  interesting  to  note  that  in  certain  members  of  the 
vegetable  kingdom  are  to  be  found  enzymes  very  similar 
to  the  normal  ones  of  animal  origin  just  considered,  and 
that  where  the  latter  appear  to  be  deficient  in  quantity  or 
action  these  kindred  ones  may  sometimes  be  used  with 
advantage.  Thus,  in  the  pineapple  and  in  the  papaw  are 
ferments  akin  to  pepsin  or  trypsin,  and  in  the  former 
another  with  the  same  action  as  rennin.  All  are  familiar 
with  the  diastase  of  germinating  seeds  and  its  use  in  the 
making  of  malt;  but  not  so  common  is  the  knowledge  that 
other  seeds  contain  fat-splitting  enzymes  much  likesteapsin. 
But  though  these  and  other  extraneous  digestants  may  be 
valuable  and  advantageous  as  therapeutic  agents  when  an 
actual  lessening  or  cessation  of  normal  function  makes 
them  necessary,  a  caution  should  be  interpolated  here 
regarding  the  habit  that  may  be  acquired  of  depending 
too  much  upon  them,  especially  by  persons,  otherwise 
healthy,  whose  digestive  functions  are  somewhat  defi- 
cient. A  better  plan  is  to  bring  those  functions  up  to  the 
normal  in  strength  and  vigor  by  the  observance  of  hygienic 
rules  and  a  well-considered  method  of  life. 


FOOD  NECESSARY  TO  LIFE  AND  HEALTH     243 

THE  AMOUNT  OF  FOOD  NECESSARY  TO  LIFE 
AND  HEALTH. 

Considerable  work  has  been  done  to  determine  just 
what  amount  of  the  proximate  food-principles  the 
average  person  requires  daily,  and  in  this  respect  Mole- 
schott's  tables  are  quite  generally  accepted,  having  been 
constructed  from  data  gained  by  actual  experiment  and 
also  by  the  continued  observation  of  the  effects  of  a 
number  of  dietaries.  According  to  these  tables,  a  man 
weighing  160  pounds  and  doing  work  equivalent  to  300 
foot-tons  per  diem  will  need  about  4.6  ounces  of  proteids, 
3  ounces  of  fats,  14.25  ounces  of  carbohydrates,  and  a 
little  more  than  1  ounce  of  salts.  Vaughan  believes  that 
the  average  working-man  in  America  requires  daily,  in 
round  numbers,  not  less  than  four  ounces  of  proteids,  two 
ounces  of  fats,  and  eighteen  ounces  of  carbohydrates. 
Chittenden  has  recently  claimed  that  four  ounces  of 
proteids  is  considerably  more  than  is  necessary  to  main- 
tain health,  but  the  quantities  given  are  the  ones  generally 
accepted  by  physiologists. 

It  is  essential  that  the  proper  proportion  between  the 
ingested  nitrogen  and  carbon  should  be  maintained,  and 
this  should  be  as  one  of  the  former  to  fifteen  of  the  latter. 

In  addition,  the  individual  needs  from  70  to  100  fluid- 
ounces  of  water  daily,  a  good  part  of  which,  however,  is 
normally  taken  with  the  food.  It  must  be  remembered 
that  the  above  figures  represent  only  average  amounts, 
and  that  climate,  amount  of  exercise,  the  size  and  activity 
of  functional  and  excretory  organs,  and  personal  peculiari- 
ties all  serve  to  modify  them  in  the  case  of  any  special 
individual. 

Other  conditions  not  interfering  too  greatly,  any  com- 
bination of  foods  giving  the  above  amounts  of  tlie  proxi- 
mate principles  at  a  reasonable  cost  will  be  an  economical 
and  healthful  diet,  provided  such  food  is  acceptable  to  the 
palate,  is  digestible,  and  contains  nothing  harmful  to  the 
system,  and  that  it  include  the  essential  accessory  sub- 


244  FOOD 

stances  or  so-called  vitamines  that  recent  research  seems 
to  prove  necessary  to  health  and  well-being.^ 

"Liberal  consumption  of  all  of  the  essential  constitu- 
ents of  a  normal  diet,  prompt  digestion  and  absorption 
and  prompt  evacuation  of  the  undigested  residue  from 
the  intestine  before  extensive  absorption  of  products  of 
bacterial  decomposition  of  proteins  can  take  place,  are 
the  optimum  conditions  for  the  maintenance  of  vigor  and 
the  characteristics  of  youth. "^ 

Fothergill  thinks  that,  as  a  rule,  we  take  too  much  pro- 
teid  food,  especially  in  the  form  of  meat,  and  that,  though 
this  goes  in  the  main  for  tissue-repair,  the  latter  requires 
much  less  of  such  food  than  we  ordinarily  suppose,  and 
that  the  system  does  not  need  so  very  much  of  albumen 
or  its  equivalents.  In  this  he  may  be  correct  to  a  certain 
degree,  particularly  as  regards  his  fellow-Englishmen,  who 
are  notorious  meat-eaters,  and  as  to  the  facts  that  tissue- 
waste  is  comparatively  slight  and  that  the  body  frame- 
work rusts  out  rather  than  burns  out.  But  in  addition 
to  the  statements  already  made — that  part  of  our  nitrog- 
enous food  regulates  the  demand  for  oxygen,  that  part  is 
doubtless  a  source  of  energy,  and  that  still  another  part 
may  be  converted  into  fat — we  should  also  remember  that 
animal  food  is  a  concentrated  food,  that  much  energy  has 
been  expended  in  converting  and  storing  it  from  the 
vegetable  world,  that  it  is  stimulating  and  often  appetiz- 
ing, and  that  our  digestive  organs  resemble  more  closely, 
at  least  as  far  as  comparative  weight  is  concerned,  those 
of  the  carnivora  rather  than  of  the  herbivora.  These 
reasons,  as  well  as  the  fact  that  animal  proteids  make  up 
a  considerable  part  of  the  only  typically  complete  food 
which  we  have  and  which  nature  gives  to  the  mammalian 
infant,  would  seem  to  indicate  that  we  should  be  careful 

^  For  such  combinations,  see  Vaughan's  Healthy  Homes  and  Foods 
for  the  Working  Classes;  and  Mrs.  Abel's  Practical,  Sanitary,  and 
Economic  Cooking.  Both  are  essays  published  by  the  American  Public 
Health  Association. 

2  McCollum:     The  Newer  Knowledge  of  Nutrition,  p.  148. 


FUNCTIONS  OF  FOOD-PRINCIPLES  245 

not  to  use  too  little  nitrogenous  food.  On  the  other 
hand,  the  experiments  of  Chittenden  and  others  tend  to 
show  that  careful  and  thorough  mastication  automatically 
lessens  the  desire  for  and  consumption  of  proteids,  with  a 
resultant  increase  in  one's  powers  of  endurance  and  free- 
dom from  fatigue.  This  does  not  prove,  however,  that  the 
proteids  that  are  consumed  should  necessarily  all  be  from 
a  vegetal  source. 

The  proteid  portion  of  our  food  is  obtained  from  the 
albumin  of  meat  and  fish,  from  milk  and  eggs,  and  from 
the  gluten  of  cereals  and  the  vegetable  casein  (albumin) 
of  the  leguminous  plants,  such  as  peas,  beans,  etc.  The 
proportion  and  properties  of  the  albuminous  matter  vary, 
of  course,  in  each  of  these,  and  even  in  the  same  sub- 
stances under  different  circumstances;  but  all  should  be 
taken  into  consideration  and  used  interchangeably  if  we 
wish  to  obtain  the  greatest  variety  and  benefit  in  feeding, 
together  with  due  economy  of  expense. 

In  this  connection  attention  may  again  be  directed  to 
the  notable  fact  that  the  leguminous  plants,  through  the 
aid  of  certain  species  of  bacteria,  are  able  to  absorb  and 
store  up  in  the  form  of  proteids  a  considerable  quantity 
of  nitrogen  from  the  surrounding  atmosphere,  and  that 
these  plants  are,  therefore,  an  important  source  of  food- 
supply. 

The  carbohydrates  that  furnish  food  to  the  body  and 
are  one  of  the  sources  of  the  heat  and  energy  upon  which 
muscular  motion  and  vital  activity  depend,  are  practically 
all  derived,  with  the  exception  of  milk-sugar,  from  the 
starches,  sugars,  and  gums  of  the  vegetable  kingdom. 

It  has  been  shown  that  much  the  greater  part  of  the 
digestion  of  carbohydrate  food  is  due  to  the  action  of 
the  pancreatic  enzyme  amylopsin;  but  we  should  not 
forget  the  action  of  the  saliva,  nor  that  thorough  mastica- 
tion greatly  assists  the  subsequent  digestion  by  breaking 
up  the  starch  granules  and  exposing  them  more  freely  to 
the  action  of  the  digestive  juices.  The  latter  object  is 
also  obtained  by  crushing  the  cereals  and  by  cooking  the 


246  .  FOOD 

starch-containing  foods,  for  "grinding  and  cooking  lessen 
the  labor  of  the  jaws  and  salivary  (and  pancreatic) 
glands.'' 

After  the  end-products  (dextrose,  levulose,  etc.)  of 
carbohydrate  digestion  have  been  absorbed  from  the 
alimentary  canal,  part  of  them,  at  least,  are  reconverted 
in  the  liver  into  animal  starch  or  glycogen,  and  this  por- 
tion becomes  a  part  of  the  body-store  of  fuel.  Fothergill 
says:  "The  liver  stores  up  from  each  meal  so  much 
glycogen  and  gives  it  off  as  required;  otherwise  life  would 
only  be  one  dreary  meal."  Another  and  perhaps  greater 
moiety  of  the  digested  carbohydrates  is  converted  into 
fat  and  stored  as  adipose  tissue  in  various  parts  of  the 
body,  as  a  further  reserve  of  fuel  for  any  emergency. 
"Many  authorities  state  that  fat  is  formed  directly  from 
carbohydrates,  and  the  weight  of  evidence  appears  to 
favor  this  view;  but  whether  it  is  so  formed  directly,  or 
indirectly  by  retarding  the  metabolism  of  the  fatty  and 
proteid  constituents  of  the  food,  there  is  no  doubt  that 
the  consumption  of  carbohydrates  results  in  the  forma- 
tion of  fat  within  the  body."^  Moreover,  "whatever  the 
mixture  of  fats  taken  in  as  food,  the  fat  of  the  body  always 
has  the  same  composition;  this  fact  agrees  with  the  con- 
clusion that  the  metabolism  and  deposition  of  fat  in  the 
body  are  due  to  cell  activity,  and  that  the  fat  comes  in 
part  from  the  proteid  and  part  from  the  carbohydrate 
foods."2 

Another  important  function  of  the  carbohydrate  foods 
is  the  formation  by  their  metabolism  in  the  body  of  lactic 
and  other  acids,  which  are  of  the  greatest  value  in  nutri- 
tion and  in  maintaining  the  normal  reactions  of  the  body- 
fluids  This  is  perhaps  one  of  the  chief  reasons  why  fats 
and  carbohydrates  are  not  interconvertible  in  any  pro- 
longed dietary. 

Fat  is  essentially  a  compound  of  glycerin  with  one  or 
more  fatty  acids,  usually  stearic,  palmitic,  and  oleic.    The 

^  Notter  and  Firth,  Treatise  on  Hygiene,  p.  254. 
2  Ibid.,  p.  253. 


CONSTRUCTIVE  IMPORTANCE  OF  FAT  247 

digestibility  of  a  fat  largely  depends  upon  its  being  fluid 
at  the  body-temperature;  therefore,  as  the  melting-point 
of  stearin  is  higher  than  this,  the  more  of  it  that  a  fat 
contains,  the  less  digestible  and  nutritious  will  the  latter 
be.  For  this  reason  butter  is  more  digestible  than  suet, 
lard  than  mutton-fat,  etc.,  and  the  more  assimilable  cod- 
liver  oil  is  that  from  which  the  stearin  has  been  removed. 

Fat  for  food  is  derived  from  vegetable  as  well  as  animal 
sources,  many  seeds  and  nuts  and  some  cereals,  as  oats 
and  corn  (maize),  containing  much  fat.  By  improved 
methods  it  is  becoming  possible  to  supply  fats  in  purer, 
cheaper,  and  more  agreeable  forms,  so  that  they  may  now 
be  freely  used  even  by  the  poor,  the  very  class  that  needs 
them  most.  "Butter  fat  and  egg-yolk  fat  contain  a 
growth-promoting  ingredient  (as  does  cod-liver  oil)  which 
appears  to  be  more  or  less  completely  wanting  in  other 
dietary  fats  of  both  animal  and  vegetable  origin."^ 

Under  normal  conditions  it  is  probable  that  the  body- 
fat  or  adipose  tissue  is  almost  never  derived  from  the 
fat  in  food  but  rather,  as  stated,  from  the  proteids  and 
carbohydrates;  but  fat  is  also  an  essential  part  of  tissue- 
structure,  making  up  more  than  one-fifth  of  the  solid 
matter  of  the  brain  and  nerve  tissues  and  one-sixth  of 
muscle,  and  possibly  serving  as  fuel  when  the  cell-con- 
tents are  oxidized;  and  it  is  probable  that  this  fat  of 
active  tissues  comes,  at  least  in  part,  from  that  ingested  as 
food.  It  is  also  probable  that  the  digested  fats  or  their 
acids  enter  into  combination  with  certain  organic  sub- 
stances in  the  intestinal  canal  or  in  the  lymph  or  blood, 
the  resulting  compounds  being  intermediate  to  ones 
still  higher  and  essential  in  the  structure  of  vital  and 
active  cells.  Adami'^  has  shown  that  in  fatty  degenera- 
tions and  other  pathological  processes,  as  well  as  in  many 

^  Mendel,  Journal  of  the  American  Medical  Association,  September 
5,  1914,  Ixiii,  No.  10,  822. 

*  The  Myelins  and  Potential  Fluid  Crystalline  Bodies  of  the  Organism, 
Journal  of  the  American  Medical  Association,  February  9,  1907,  pp. 
463-469. 


248  FOOD 

normal  tissues,  so-called  ^^  myelin  globules"  are  to  be 
found.  These  myelin  globules  prove  to  be  compounds 
of  cholesterin  or  of  cholin  or  neurin  with  fatty  acids. 
Moreover,  lecithins,  which  are  found  in  every  cell  and 
abundantly  in  the  brain  and  nerves,  as  well  as  in  blood 
corpuscles  and  lymph,  in  breaking  up  dissociate  into 
fatty  acids,  glycerophosphoric  acid  and  cholin,  qr,  accord- 
ing to  Carbone,  into  fatty  acids,  neutral  fats  and  choles- 
terin. Beyond  the  lecithins  is  protagon,  "which  is 
obtained  especially  from  the  brain  and  is  a  crystalline 
body  containing  lecithin  and  cerebrin."  Thus  it  is  seen 
how  the  derivatives  from  the  fat  in  the  diet  become 
incorporated  as  component  parts  of  the  most  complex 
tissues  and  organs.  In  any  case,  however,  fat  is  a  very 
important  part  of  a  man's  diet,  for  not  only  is  a  small 
quantity  necessary  to  the  digestion  of  proteids,  causing 
the  formation  in  the  body  of  larger  amounts  of  fat  than 
the  quantity  ingested  and  greatly  improving  the  physical 
condition;  but  it  may  be  and,  when  occasion  requires, 
undoubtedly  often  is  used  directly  as  fuel  without  first 
being  stored  in  the  tissues. 

As  fat  is  a  concentrated  fuel-food,  it  is  to  be  used  freely 
when  we  want  to  keep  the  body  warm  or  when  we  need 
extra  force  for  any  increased  exertion.  "On  a  diet  rich 
in  fat  great  muscular  effort  can  be  undergone  with  but 
little  destruction  of  muscular  tissue,  and  without  increased 
urea  discharge."  The  object  of  fat  in  the  diet,  then,  may 
be  said  to  be  to  give  heat  and  energy  as  fuel,  and,  when 
necessary,  to  aid  in  the  repair  or  building  up  of  active 
tissue. 

The  constructive  property  of  fat  is  especially  valuable 
in  the  treatment  of  all  wasting  diseases,  especially  phthisis. 
Fothergill  emphatically  declares  that  "the  great  food  for 
the  strumous  is  fat,"  and  also  says:  "Whenever  there 
is  any  tendency  to  tubercle  the  individual  should  learn 
to  eat  fat,  just  as  a  seafaring  man  learns  to  swim.  As  a 
physician  to  a  chest  hospital,  I  have  learned  to  dread  the 
announcement  that  fat  is  no  longer  taken,  especially  if 


SALTS  AND  ACCESSORY  FOODSTUFFS  249 

the  individual  is  of  strumous  build,  with  a  small,  narrow 
chest.  In  my  opinion,  the  existence  of  a  considerable 
area  of  affected  lung  where  the  digestive  powers  keep  up 
is  less  fraught  with  evil  and  less  prognostically  significant 
than  intractable  wasting  with  very  little  disease  in  the 
lung."  In  this  connection,  note  that  an  excess  of  pro- 
teids  in  the  diet  causes  a  more  rapid  oxidation  of  fat,  and 
that  an  excess  of  fat  or  of  carbohydrates  lessens  the 
absorption  of  oxygen  and  the  oxidation  of  both  fats  and 
proteids.  Also,  that  the  free  use  of  fluids  is  thought  to 
favor  an  increase  in  thequantity  of  fat  deposited  in  the  body. 

Fat  is  practically  indigestible  in  the  stomach,  and  some 
stomachs  cannot  tolerate  it,  especially  when  taken  with 
other  food;  although  usually  a  little  fat  assists  in  the 
digestion  of  proteids  by  stimulating  the  secretion  of  the 
gastric  juice.  Cases  occur  not  rarely  in  which  it  is  neces- 
sary that  comparatively  large  quantities  of  fat  should  be 
ingested  and  yet  in  which  there  is  apparently  decided  gas- 
tric intolerance  of  it.  In  such  event  success  is  often  to 
be  attained  by  giving  the  fat  some  little  time  after  the 
regular  meals,  when  the  gastric  digestion  is  approaching 
completion  and  the  chyme  is  being  passed  out  of  the 
stomach  to  be  further  subjected  to  the  action  of  the  intes- 
tinal digestants.  It  may  also  be  well  to  partially  or 
wholly  emulsify  it,  especially  if  there  be  faulty  secretion 
of  bile  and  pancreatic  juice,  and  sometimes  to  disguise  its 
taste  with  agreeable  aromatics  or  flavors.  In  this  way 
there  is  generally  but  little  trouble  in  administering  fats, 
even  such  as  those  which,  like  cod-liver  oil,  have  a  dis- 
agreeable taste  and  odor.  Failing  in  this,  we  may  still 
resort  to  inunctions,  preferably  of  predigested  or  emulsi- 
fied fats,  and  often  with  considerable  advantage,  since  it 
has  been  experimentally  shown  that  after  passing  through 
the  skin  fat  may  be  taken  up  by  the  subcutaneous  lym- 
phatics and  later  be  oxidized  or  metabolized  almost  as  com- 
pletely as  if  it  had  entered  the  system  by  way  of  the 
intestinal  canal  and  thoracic  duct. 

Certain  salts  in  definite  proportions  are  necessary  for 


250  FOOD 

the  maintenance  of  health  in  the  body.  "Lime,  chiefly 
in  the  form  of  phosphate,  is  absent  from  no  tissue,  and 
there  is  reason  to  think  that  no  cell-growth  can  go  on 
without  it/'  Even  the  bacteria  must  have  earthy  phos- 
phates for  the  purposes  of  growth.  Chlorine,  derived 
largely  from  the  sodium  chloride  of  food,  is  necessary  to 
form  the  hydrochloric  acid  of  the  gastric  juice,  the  chlo- 
rides also  keeping  in  solution  the  globulins  of  the  blood 
and  body-fluids  and  helping  to  dissolve  the  albumin. 
Phosphorus  is  necessary  in  the  formation  of  the  lecithin 
of  nerve-tissues,  as  well  as  for  the  phosphates  above  men- 
tioned, and  those  of  potassium,  magnesium,  etc.,  which 
go  to  form  bone.  Potassium  salts  maintain  the  alkalinity 
of  the  solid  tissues,  and  sodium  salts  that  of  the  body- 
fluids.  Iron  is  essential  for  the  construction  and  nutri- 
tion of  the  blood-corpuscles,  though  small  quantities  of  it 
are  to  be  found  in  almost  every  other  tissue. 

But  not  only  must  the  above  inorganic  salts  be  given 
in  proper  supply,  but  also  certain  ones  of  organic  nature, 
in  order  to  prevent  conditions  of  malnutrition  or  disease. 
Those  especially  which  are  changed  to  form  carbonates, 
as  the  lactates,  tartrates,  etc.,  or  their  respective  acids, 
help  to  maintain  the  alkalinity  of  the  system  and  appear 
to  be  most  essential,  as  a  scorbutic  condition  seems  to  be 
inevitably  created  or  fostered  by  their  absence.  There  is 
also  some  evidence  that  certain  gouty  conditions  may  be 
due  to  the  removal  of  the  natural  vegetable  salts  by 
improper  methods  of  cooking.  The  fact  of  the  carbohy- 
drates being  an  important  source  of  these  organic  acids 
and  salts  has  already  been  mentioned. 

As  a  review  of  the  preceding  statements,  the  following 
quotation,  from  Notter  and  Firth,^  may  be  of  value: 

"With  regard  to  the  necessity  for  all  four  classes  of 
aliments,  it  can  be  affirmed  with  certainty  that  (putting 
scurvy  out  of  the  question)  men  can  live  for  some  time 
and  can  be  healthy  with  a  diet  of  proteids,  fats,  salts,  and 

*  Treatise  on  Hygiene,  p.  256. 


SALTS  AND  ACCESSORY  FOOD-STUFFS         251 

water.  But  special  conditions  of  life,  such  as  great  exer- 
cise or  exposure  to  very  low  temperature,  appear  to  be 
necessary,  and  under  usual  conditions  of  life  health  is  not 
very  perfectly  maintained  on  such  a  diet.  It  has  not  yet 
been  shown  that  men  can  live  in  good  health  on  proteids, 
carbohydrates,  salts  and  water,  without  fat. 

"The  exact  effect  produced  by  the  deprivation  of  any 
one  of  these  classes  is  not  yet  known.  An  excess  of  the 
proteids  causes  a  more  rapid  oxidation  of  fat,  while  an 
excess  of  fat  lessens  the  absorption  of  oxygen  and  hinders 
the  metamorphosis  of  both  fatty  and  albuminous  tissues. 
The  carbohydrates  have  the  same  effect  when  in  excess, 
and  appear  to  lessen  the  oxidation  of  the  two  other 
classes. 

"It  is  generally  admitted  that  the  success  of  Banting's 
treatment  of  obesity  is  owing  to  two  actions :  the  increased 
oxidizing  effect  on  fat  consequent  on  the  increase  of  meat 
(especially  if  exercise  be  combined),  and  the  lessened 
interference  with  the  oxidation  of  fat  consequent  on  the 
deprivation  of  starches. 

"Health  cannot  be  maintained  on  proteids,  salts,  and 
water  alone;  but,  on  the  other  hand,  it  cannot  be  main- 
tained without  them." 

Lastly,  with  many  of  our  foods  we  require  the  addition 
of  certain  flavors,  condiments,  etc.,  which,  though  they 
have  little  or  no  real  food-value  in  themselves  in  the 
sense  of  repairing  tissue  or  furnishing  energy,  do  much 
good,  when  not  abused,  by  making  the  food  more  pala- 
table, by  stimulating  the  secretion  of  the  digestive  fluids, 
and  by  acting  as  carminatives.  These  condiments  should 
not  be  omitted  from  the  food  of  the  sick  or  convalescent, 
for  they  have  a  value  of  their  own,  and  are  "agreeable 
to  the  palate  and,  in  moderation,  good  for  the  digestive 
organs. '^ 

Reference  has  already  been  made  to  the  recently  dis- 
covered importance  of  the  so-called  vitamines. 

"Through  the  'vitamine'  hypothasis,  Funk  attempted 
to  account  for  the  diseases  beri-beri,  scurvy,  pellagra  and 


252  FOOD 

rickets,  as  being  each  due  to  the  lack  of  a  specific  chemical 
substance,  a  'vitamine'  in  the  diet.  This  was  a  very 
logical  conclusion  from  the  data  available  to  Funk. 
There  has  since  been  secured  much  experimental  evi- 
dence in  support  of  the  view  that  scurvy  and  pellagra 
do  not  arise  from  deficiency  in  the  diet  of  specific  chemi- 
cal substances  in  the  sense  in  which  suggested,  and  this 
seems  to  be  true  also  of  rickets."  On  the  other  hand, 
McCollum^  and  others  seem  to  have  demonstrated  that 
while  there  is  not  a  specific  "vitamine"  for  each  so-called 
"deficiency  disease,"  the  diet  must  contain,  in  addition 
to  the  long-recognized  dietary  factors,  viz.:  proteins, 
carbohydrates  and  fats,  and  a  suitable  supply  of  certain 
organic  and  inorganic  salts,  two  as  yet  unidentified  sub- 
stances or  groups  of  substances.  One  of  these  is  associated 
with  certain  fats,  and  is  especially  abundant  in  butter  fat, 
Ggg  yolk  and  the  fats  of  the  glandular  organs  such  as  the 
liver  and  kidney,  but  is  not  found  in  any  fats  or  oils  of 
vegetable  origin.  The  second  substance  or  group  of  sub- 
stances of  chemically  unidentified  nature  is  never  associated 
with  fats  or  oils  of  either  animal  or  vegetable  origin.  It 
is  widely  distributed  in  natural  foods,  and  can  be  isolated 
in  a  concentrated,  but  not  a  pure  form,  from  natural  food- 
stuffs by  extraction  of  the  latter  with  either  water  or 
alcohol.  This  water  or  alcoholic  extract  always  contains 
the  substance  which  cures  polyneuritis  (otherwise  known  as 
beri-beri) . 

For  these  two  substances  or  groups  of  substances,  as 
yet  chemically  unidentified,  McCoUum  and  Kennedy  have 
proposed  the  terms  "fat-soluble  A"  and  "water-soluble 
"B."  The  former  of  these,  which  is  also  to  be  found  in 
the  leaves  of  plants  and  is  fairly  abundant  in  the  germs 
of  seeds,  but  not  in  the  stored  up  food  reserve  of 
seeds,  roots,  tubers,  nor  in  animal  flesh  (muscle), 
seems   to   be   absolutely   essential   for   growth   and    the 

^  McCollum:     The  Newer  Knowledge  of  Nutrition,  pp.  30-31. 


MILK  253 

maintenance  of  health  in  the  body.  It  also  prevents  the 
development  of  a  disease  of  the  eyes  known  as  exoph- 
thalmia,  while  the  second  substance,  the  "fat-soluble  B." 
prevents,  as  stated,  the  development  of  beri-beri.  It 
would  thus  seem  that  the  two  maladies  just  mentioned 
are,  strictly  speaking,  the  only  known  "deficiency  dis- 
eases" due  to  the  lack  of  a  specific  substance  or  "vita- 
mine"  in  the  diet.  On  the  other  hand,  while  faulty 
diet  is  imdoubtedly  a  factor  in  the  causation  of  such 
diseases  as  scurvy,  rickets  and  pellagra,  it  has  been 
shown  that  no  one  of  these  is  due  to  the  lack  of  such 
specific  substances  alone,  but  that  additional  factors, 
such  as  the  presence  of  infective  organisms,  lack  of 
certain  proteins  or  salts,  etc.,  will  satisfactorily  account 
for  the  development  of  one  or  the  other  of  these  maladies. 
It  will  be  impossible  to  go  into  details  concerning  all 
the  articles  commonly  used  as  foods,  but  there  are  certain 
facts  that  should  be  well  known  and  which  cannot  properly 
be  omitted  from  a  work  of  this  kind. 

MILK. 

Milk  is  a  typical  foodstuff,  complete  in  itself,  in  that  it 
contains  all  the  food-principles  and  these  in  nearly  the 
proper  proportion,  at  least  for  infant  life.  The  casein  and 
albumin  represent  the  proteids;  the  cream,  the  fats;  and 
the  lactose  or  milk-sugar  is  a  concentrated  carbohydrate — 
all  being  in  combination  with  sufficient  salts  and  water. 

Milk  should  constitute  almost  the  sole  food  of  infants 
during  the  earlier  months  of  life;  and  that  it  is  capable  of 
sustaining  adult  life  almost  indefinitely,  especially  where 
there  is  little  demand  for  heat  or  the  expenditure  of  force, 
has  been  shown  in  numerous  instances.^  Coplin  and 
Bevan  mention  the  case  of  a  patient  who  lived  and  thrived 

•  It  is  understood,  of  course,  that  in  order  to  be  a  proper  food  for 
young  infants,  cows'  milk  must  be  modified  so  as  to  resemble  human 
milk  as  nearly  as  possible,  and  so  as  to  give  the  proportion  of  the  respec- 
tive food-principles  which  each  particular  case  may  need. 


254  FOOD 

on  milk  alone  for  over  thirteen  months,  and  of  another 
who  lived  for  three  years  on  the  same  diet.  But  the 
limited  proportion  of  carbohydrates,  even  though  concen- 
trated, is  not  all-sufficient  for  the  maintenance  of  great 
vital  activity,  and  for  persons  in  ordinary  life  some  addi- 
tion to  the  diet  is  necessary. 

The  albumin  of  milk  is  coagulated  by  heat,  but  the 
casein,  which  constitutes  the  greater  part  of  the  proteid 
element,  is  clotted  by  an  acid  or  by  an  enzyme  such  as 
rennin;  and  as  both  acid  and  rennin  are  present  in  normal 
gastric  juice,  it  would  seem  that  the  preliminary  coagula- 
tion of  casein  was  essential  to  its  proper  digestion.  It 
should  be  remembered,  however,  that  the  casein  of  cows' 
milk  forms  a  much  harder  and  firmer  clot  than  does  that 
of  human  milk,  and  that  the  former  should,  therefore, 
never  be  hastily  introduced  into  the  stomach  in  large 
volumes,  but  should  rather  be  taken  slowly  and  preferably 
with  other  food  which  will  help  to  disintegrate  the  curd. 
In  the  feeding  of  children,  an  alkali,  such  as  lime-water, 
when  mixed  with  the  milk,  is  thought  to  soften  the  curd 
and  possibly  to  facilitate  digestion. 

Outside  of  the  body,  fermentative  changes  due  to  certain 
bacteria  may  convert  the  milk-sugar  into  lactic  acid,  which 
coagulates  the  casein  and  "sours"  the  milk.  Another 
peculiarity  of  casein  is  the  tenacity  with  which  it  holds 
large  quantities  of  phosphate  of  lime,  one  of  the  most 
valuable  of  food-salts. 

Sometimes  it  is  advantageous  or  necessary  to  predigest 
milk  for  infants  or  sick  persons,  but  if  the  digestion  be 
carried  beyond  a  certain  point,  the  consequent  peptones 
and  albumoses  will  give  the  milk  a  bitter  and  disagreeable 
taste.  In  the  feeding  of  infants  it  must  not  be  forgotten 
that  the  percentage  composition  of  human  milk  is  different 
from  that  of  cows'  milk,  and  that  the  latter  will  need 
dilution  to  decrease  the  proteid  proportion,  and  also  an 
increase  of  fat  and  carbohydrates.  As  a  child  grows  older 
and  more  active,  it  becomes  necessary  to  add  to  the 
milk  additional  carbohydrates,  which  should  be  easy  of 


PASTEURIZATION  OF  MILK  255 

digestion  and  soluble,  milk-sugar  and  predigested 
starches  in  the  form  of  maltose  and  its  allies  being 
preferable. 

Milk  should  always  be  kept  as  cool  as  possible  and  in 
closed  vessels,  not  only  to  prevent  it  from  absorbing  dis- 
agreeable odors  and  harmful  gases,  which  it  is  very  prone 
to  do,  but  to  exclude  dirt  and  bacteria  as  well.  As  it  is 
an  excellent  culture-medium,  and  as  it  is  commonly  liable 
to  be  exposed  to  contamination  by  organisms  from  many 
sources  before  it  reaches  the  consumer,  fermentative  or 
other  harmful  chemical  changes  are  almost  certain  to 
occur  in  it  if  the  temperature  conditions  are  at  all  favor- 
able. For  this  reason  it  is  necessary  that  the  greatest 
care  should  be  used  in  the  handling  of  the  milk  from  the 
time  it  leaves  the  cow  until  it  is  used,  and,  for  the  feeding 
of  children  and  whenever  there  is  any  possibility  of  it 
being  the  carrier  of  disease  germs  of  any  kind,  it  should 
be  properly  pasteurized  or  sterilized  and  then  kept  free 
from  further  contamination  until  used.  .  In  fact,  pas- 
teurized milk,  modified  to  resemble  the  human  secre- 
tion, will  usually  be  superior  to  any  other  artificial  food 
for  infants,  but  the  operation  should  always  be  done 
before  fermentation  has  begun  and  harmful  products 
have  been  developed  in  the  milk.  Sterilization  may 
slightly  alter  the  taste  and  other  properties  of  the  milk 
by  coagulating  the  abumin,  but  it  is  doubtful  whether 
it  makes  any  real  change  in  its  digestibility. 

Pasteurization. — "By  pasteurization  is  meant  raising  the 
temperature  of  the  milk  to  such  an  extent  and  for  a 
sufficiently  long  period  as  to  ensure  the  destruction  of 
the  lactic  acid  bacteria  and  pathogenic  organisms  with- 
out affecting  the  enzymes  or  the  lactalbumin."^  Accord- 
ingly, for  a  general  standard  the  minimum  temperature 
and  duration  of  time  for  successful  pasteurization  may 
be  respectively  placed  at  60°  C.  (140°  F.)  and  twenty 
minutes,  although  temperatures  much  higher  and  varying 

»  Harrington,  5th  ed.,  p.  119. 


256  FOOD 

exposures,  both  shorter  and  longer,  are  employed,  de- 
pending upon  the  kind  of  apparatus  or  method  used. 

Milk  that  has  been  pasteurized  is  not  entirely  sterile; 
consequently  it  should  be  cooled  quickly  and  be  kept  at 
a  low  temperature  until  used.  Otherwise  the  saprophytic 
bacteria  surviving  the  process  may  multiply  rapidly,  espe- 
cially as  they  are  now  deprived  of  the  destroying  or  retard- 
ing influence  of  the  lactic  acid  bacteria,  and  may  even  pro- 
duce harmful  decomposition  products  in  the  milk,  which 
remains  sweet  and  apparently  free  from  harm.  For  the 
same  reason,  it  is  a  better  culture  medium  even  than  raw 
milk  for  whatever  new  organisms  gain  access  to  it,  where- 
as the  laity  are  apt  to  think  that  the  pasteurizing  process 
has  rendered  it  safe  for  an  indefinite  time  and,  therefore, 
to  be  more  careless  regarding  its  protection  than  if  it 
were  delivered  to  them  in  its  natural  state. 

For  these  reasons  and  because  there  seems  to  be  some 
evidence  that  pasteurized  milk  may  not  be  as  wholesome, 
especially  for  young  children,  as  the  natural  fluid,  the 
writer  feels  that  the  pasteurization  of  a  public  milk  supply 
is  only  to  be  advocated  or  approved  when  it  is  manifestly 
impossible  or  impracticable  to  secure  the  observance  of 
all  of  the  sanitary  procedures  whereby  it  may  be  trans- 
mitted in  a  safe  and  wholesome  condition  from  cow  and 
dairy  to  the  actual  consumer.  On  the  other  hand,  home 
pasteurization  may  be  most  advisable,  particularly  if 
there  is  any  suspicion  of  infection,  as  in  time  of  epidemics, 
or  where  opportunity  for  home  refrigeration  and  proper 
care  are  lacking. 

The  cream  of  milk  is  fat  in  its  most  digestible  and 
acceptable  form,  and  should  not  be  removed  from  milk  if 
the  latter  is  to  be  used  as  food.  If  the  milk  seems  to  be 
too  rich,  it  may  be  advisable  to  skim  it,  giving  it  in  some 
form  or  other  with  the  regular  meal,  and  reserving  the 
cream  until  a  couple  of  hours  or  so  later,  when  gastric 
digestion  is  approaching  completion.  One  may  also  often 
avoid  the  use  of  cod-liver  oil  and  similar  fats  by  taking 
cream — either  plain  or  whipped  and  flavored — in  this  way 


DISEASES  DUE  TO  MILK  257 

i.  e.,  some  little  time  after  the  meals.  It  should  not  be 
forgotten  that,  according  to  Mendel,  McColluni  and 
others,  the  fat  of  cream  and  eggs  contains  an  important 
growth  promoting  ingredient,  which  is  much  less  abundant 
or  entirely  lacking  in  other  commonly  used  fats. 

"Milk  is  just  as  necessary  in  the  diet  of  the  adult  as 
in  that  of  the  growing  child.  Any  diet  which  will  not 
support  normal  development  in  the  young  will  not 
support  optimum  well-being  in  the  adult.  Milk  is  our 
greatest  protective  food,  and  its  use  must  be  increased. 
The  price  must  be  allowed  to  go  up,  so  long  as 
the  cost  of  production  makes  it  necessary,  and  up  as 
far  as  is  essential  to  make  milk  production  a  profitable 
business.  Unless  this  is  done,  the  effects  will  soon 
become  apparent  in  a  lowering  of  our  standards  of  health 
and  efficiency."^ 

Skimmed  milk  and  buttermilk  may  be  used  freely  as 
beverages,  as  both  are  refreshing  and  healthful  with  some 
little  food-value;  buttermilk  is  also  acceptable  to  many 
persons  on  account  of  its  lactic  acid.  "Koumiss"  and 
"kefir"  are  both  prepared  from  milk  through  the  action 
of  certain  fermentative  organisms,  which  also  bring  about 
a  partial  digestion  of  the  casein.  Each  contains  carbonic 
and  lactic  acids,  though  in  difi^erent  proportions,  some  pep- 
tones or  albumoses,  and  a  very  little  alcohol.  They  are 
wholesome,  agreeable  to  most  palates,  and  are  usually 
retained  and  utilized  by  stomachs  rebellious  to  almost  all 
other  foods.  Furthermore,  Metchnikofl"^  strongly  advo- 
cates their  use,  since  lactic  acid  and  the  micro-organisms 
that  cause  its  formation  are  antagonistic  to  the  microbes 
of  putrefaction,  which  multiply  only  in  alkaline  substances. 
The  beverages  mentioned,  therefore,  tend  to  prevent  the 
development  in  the  intestinal  canal  of  such  putrefactive 
germs  and  of  ptomains  and  other  poisonous  products  of 
decomposition  which,  when  absorbed  into  the  circulation, 
give  rise  to  the  manifold  symptoms  of  auto-intoxication. 

1  McCoUum:     The  Newer  Knowledge  of  Nutrition,  p.   153. 

2  The  Nature  of  Man.  Chapter  X. 

17 


258  FOOD 

Milk  may  be  a  factor  in  the  causation  of  disease  in  a 
number  of  ways.  Large  and  tough  curds  of  cows'  milk 
in  the  stomach  often  cause  mechanical  irritation  and  indi- 
gestion, especially  in  young  children,  and  the  products  of 
the  fermentative  action  already  referred  to  are  a  frequent 
source  of  serious  intestinal  disorders;  while  if  further 
decomposition  occurs,  a  very  poisonous  ptomain,  called 
tyrotoxicon,  may  be  developed  and  may  cause  even  fatal 
results  to  those  using  the  milk.  This  same  substance 
is  also  liable  to  occur  in  any  milk-product,  such  as 
cheese  or  ice-cream,  and  is  usually  the  cause  or  agent  in 
the  cases  of  poisoning  by  such  products  that  are  so  frequently 
reported. 

Again,  the  active  principles  of  plants  which  the  cow 
has  eaten  may  be  transmitted  by  the  milk  and  produce 
their  physiological  effects.  But  a  graver  question  is 
whether  disease  may  be  transmitted  directly  from  the 
animals  to  man  by  this  almost  universal  foodstuff.  Every 
one  knows  that  the  milk  from  sick  cows  may  cause 
marked  disturbance  of  health,  and  there  is  fair  evidence 
that  cattle  are  subject  to  certain  diseases  identical  with 
or  very  similar  to  human  maladies,  the  milk  serving  as  a 
carrier  for  the  contagium. 

Though  some  authorities  still  question  whether  tuber- 
culosis can  be  thus  transmitted  unless  the  milk-glands 
themselves  are  affected,  the  great  prevalence  of  the 
disease  among  cattle  and  experimental  evidence  both  make 
it  certain  that  milk  is  often  the  means  of  transmitting  the 
infection,  and  many  believe  that  by  far  the  larger  number 
of  the  many  cases  of  infantile  tuberculosis  have  origin  from 
this  source.  The  condemnation  and  destruction  of  all 
cattle  that  show  symptoms  of  tubercular  infection  is 
certainly  one  of  the  most  important  and  effective  methods 
of  checking  the  spread  of  and  eliminating  this  very  prev- 
alent and  deadly  malady.  The  use  of  inoculations  of 
tuberculin  as  a  means  of  diagnosis  has  materially  contrib- 
uted to  this  end,  for  by  its  aid  the  presence  of  the  disease 


MILK-BORNE  EPIDEMICS  259 

is  often  indicated  in  many  animals  that  have  as  yet 
evinced  no  physical  signs  of  the  disease. 

A  British  Royal  Commission^  have  found  "that  milk 
containing  bovine  tubercle  bacilli  can,  by  feeding,  produce 
tuberculosis  in  apes,  and  they  have  no  doubt  that  many 
cases  of  human  tuberculosis,  especially  in  children,  are  due 
to  this  germ.  The  same  conclusions  had  been  reached  by 
the  United  States  Agricultural  Department's  investigators. 
The  importance  of  proper  bacteriologic  analyses  of  milk 
and  the  inspection  of  dairies  cannot  be  sufficiently  empha- 
sized, and  it  is  quite  possible  that  while  the  milk  of  tuber- 
culous cows  may  be  comparatively  innocuous  to  adults  of 
fair  resisting  powers,  it  may  be  extremely  dangerous  to 
young  children  and  those  having  a  predisposition  to 
tuberculous  infection." 

Milk,  like  other  foodstuffs,  may  also  become  a  disease- 
carrier  through  infection  from  dust  and  disease  germs, 
especially  in  the  vicinity  of  places  where  infectious  matter 
is  allowed  to  dry,  become  pulverized,  and  to  be  taken  up 
into  the  atmosphere  by  winds  and  air-currents.  But  a 
more  common  danger  is  through  carelessness  in  handling 
by  infected  persons  or  by  the  admixture  with  it  of  water 
containing  disease  germs.  Epidemics  of  diphtheria,  scar- 
let fever,  typhoid  fever,  and  cholera  have  all  been  traced 
to  contaminated  milk-supplies,  and  it  is  a  question  whether 
many  of  the  more  or  less  local  outbreaks  in  cities  are 
not  of  this  character.  The  writer  is  personally  cogni- 
zant of  five  cases  of  undoubted  scarlet  fever  that  occurred 
almost  simultaneously  in  one  locality  and  in  which, 
apparently,  the  only  common  source  was  the  milk-supply. 
He  was  unable  to  discover  that  there  had  been  any  illness 
either  among  the  cattle  or  in  the  family  of  the  milkman  in 
question,  but  he  has  always  felt  that  there  was  consider- 
able evasion  in  replying  to  the  inquiries  made.  He  also 
has  knowledge  of  a  localized  epidemic  of  typhoid  fever 

»  Journal  of  the  American  Medical  Association,  Feb.  9,  1907,  p.  52S. 


260  FOOD 

due  to  the  infection  of  a  common  milk-supply.  In  this 
instance  the  dissemination  of  the  disease  was  traced  to 
the  use  of  a  rubber  tube  for  siphoning  the  milk  from  a 
receiving  can  to  the  distributing  jars,  the  dairyman  and 
his  assistants  exhausting  the  air  from  the  same  by  suction 
by  the  mouth.  At  the  time  this  was  discovered  the 
dairyman  and  at  least  one  of  his  men  were  ill  with  typhoid 
fever  in  a  hospital. 

Newman  states  that  since  1857  more  than  one  hundred 
and  sixty  epidemics  of  typhoid  fever  have  been  traced 
to  a  polluted  milk-supply,  and  quotes  Schuder  as  saying 
"that  17  per  cent,  of  all  typhoid  epidemics  are  due  to 
the  consumption  of  infected  milk."  Moreover,  Newman 
counts  up  "some  thirty  outbreaks  of  milk-borne  diph- 
theria" and  some  seventy  of  scarlet  fever,  and  also  says 
that  "there  are  three  (other)  very  common  diseases  in 
which  milk  has  been  proved  to  play  a  not  inconsiderable 
part,  viz.,  thrush,  sore  throat,  and  diarrhea."  He  gives 
the  following  characteristics  of  milk-borne  epidemics  i^ 

(a)  There  is  a  special  incidence  of  the  disease  upon  the 
track  of  the  implicated  milk-supply.  It  is  localized  to 
such  areas. 

(6)  Better-class  houses  and  persons  generally  suffer  most. 

(c)  Milk  drinkers  are  chiefly  affected,  and  those  suffer 
most  who  are  large  consumers  of  raw  milk. 

{d)  Women  and  children  suffer  most,  and  frequently 
adults  suffer  proportionately  more  than  children. 

{e)  Incubation  periods  are  shortened. 

(/)  There  is  a  sudden  onset  and  a  rapid  decline. 

{g)  Multiple  cases  in  one  house  occur  simultaneously. 

(Ii)  Clinically,  the  attacks  of  disease  are  often  mild, 
contact  infectivity  is  reduced,  and  the  mortality  rate  is 
lower  than  usual. 

Experience  is  also  rapidly  accumulating  that  infecting 
germs  are  implanted  upon  or  in  many  foods  by  house-flies, 
roaches,  and  other  insects,  as  well  as  by  larger  vermin, 

1  Bacteriology  and  the  Public  Health,  3d  edition,  p.  218, 


PROPERTIES  OF  GOOD  MILK  261 

and  even  domestic  animals,  such  as  dogs  and  cats. 
Typhoid  bacilH  having  been  obtained  from  the  bodies  of 
flies  from  a  house  where  eight  cases  of  typhoid  fever  had 
occurred,  further  experiments  shbwed  that  flies  fed  with 
these  germs  are  able  to  convey  them  to  other  objects  for 
as  long  as  twenty-three  days  afterward.  The  bacilli  have 
also  been  found  on  the  heads,  legs,  and  wings  of  flies  five 
days  after,  and  in  their  intestines  nine  days  after  such 
feeding.^  Consequently,  every  effort  should  be  made  to 
protect  food-supplies  of  all  kinds  and  especially  milk 
from  such  contamination  by  insects  and  vermin,  especially 
in  time  of  epidemics,  for  we  should  realize  that  though 
most  of  the  cases  of  an  epidemic  may  arise  from  a  common 
source,  such  as  a  polluted  w^ater-supply  or  a  so-called 
"carrier,"  there  will  be  numerous  sporadic  cases  in  which 
the  infection  has  been  transmitted  as  above. 

The  possibility  of  milk  as  a  source  of  danger  to  health 
having  been  shown,  the  lessons  to  be  had  are  these:  that 
not  only  must  there  be  the  greatest  care  in  the  handling 
and  keeping  of  milk  until  it  is  consumed,  but  there  must 
also  be  frequent  and  careful  inspection  of  the  animals 
from  which  it  comes  and  of  their  environment;  that  no 
milk  from  any  diseased  cow  should  ever  be  used  as  food; 
that  all  who  handle  it  in  any  way  shall  be  in  good  health 
and  free  from  the  possibility  of  infecting  it;  that  wher- 
ever there  is  the  suspicion  or  possibility  of  the  milk 
being  contaminated  with  disease  germs,  it  must  be  thor- 
oughly pasteurized,  and  that  any  change  from  its  normal 
condition  should  also  forbid  its  use. 

Fortunately,  good  milk  can  almost  always  be  had  so 
cheaply  and  readily  that  no  serious  hardship  inures  by  the 
strict  observance  of  these  rules,  and  the  public  should  he 
educated  to  demand  as  well  as  to  pay  fairly  for  pure  milk 
from  healthy  animals,  these  matters  being  even  more 
important  than  that  the  quality,  as  shown  by  analysis, 
should  always  be  up  to  a  certain  standard. 

>  Ficker,  Archives  of  Hygiene,  1903,  xlvi,  274. 


262  FOOD 

Good  milk  in  bulk  should  be  opaque,  of  clear  ivory- 
white  color,  should  have  no  peculiar  smell  or  taste  nor 
leave  any  deposit  on  standing.  Nor  should  it  show  any 
change  in  taste  or  appearance  upon  boiling,  excepting 
the  formation  of  the  slight  skin  of  coagulated  albumin 
due  to  the  heating.  Details  regarding  the  composition 
of  milk  and  the  methods  for  its  examination  will  be  found 
in  the  final  chapter  of  this  volume. 

The  addition  of  preservatives  to  milk  is  very  common, 
and  should  be  discountenanced,  not  only  because  they 
are  usually  added  in  quantities  harmful  or  prejudicial  to 
health,  but  also,  and  almost  more  important,  because  milk 
should  be  supplied  to  consumers  in  such  a  condition  and 
state  as  not  to  need  the  preservative,  the  presence  of 
the  latter  being  therefore  suspicious.  The  same  reasons 
also  justify  the  condemnation  of  the  use  of  artificial 
coloring-matters.  The  chemicals  commonly  used  as  pre- 
servatives are  boric  acid,  salicylic  acid,  and  formalde- 
hyde. Of  these,  the  salicylic  acid  is  probably  most  harm- 
ful, as  the  habitual  ingestion  of  even  a  moderate  quantity 
is  apt  to  be  deleterious  to  the  kidneys.  (See  Chapter 
XIV.) 

Cheese  is  a  most  valuable  foodstuff,  and,  as  a  milk- 
product,  may  be  considered  at  this  time.  Good  cheese 
usually  contains  twice  as  much  nitrogen  and  three  times 
as  much  fat  as  the  same  weight  of  meat,  but  many 
persons  apparently  find  it  difficult  of  digestion  and  can 
eat  but  little  of  it.  This  is  perhaps  because  the  nutri- 
ment is  so  concentrated  and  because,  as  usually  eaten,  it 
forms  in  the  stomach  a  tough  or  pasty  solid  lump  into 
which  the  gastric  secretion  cannot  penetrate.  Mattieu 
Williams  has  remarked  that  we  habitually  use  cheese  in 
the  conditions  in  which  it  is  most  indigestible — either  in 
its  raw  state  or  cooked  into  a  leathery  mass — and  he  asserts 
that  if  the  cooking  is  such  that  it  is  thoroughly  mixed 
with  other  articles  of  food,  or  if  it  be  masticated  with 
other  food,  so  that  this  commingling  of  particles  takes 
place,  it  will  be  found  to  be  quite  digestible  by  almost 


EGGS  263 

every  one.  He  also  advises  the  addition  of  a  small 
amount  of  potassium  carbonate  in  the  cooking,  as  this 
favors  solution  of  the  casein  and  replaces  that  salt  which 
is  removed  in  the  whey.  As  a  food,  only  cheese  made 
from  whole  milk,  or  from  that  to  which  extra  cream  has 
been  added,  satisfies  all  requirements,  and  skim-milk 
cheeses  are  decidedly  less  nutritious  than  those  having  the 
full  proportion  of  fat. 

Butter,  consisting  as  it  does  largely  of  the  fat  of  milk, 
is  a  highly  nutritious  article  of  food  and  one  of  the  most 
digestible  of  its  class.  It  should  be  pure,  sweet,  and  free 
from  rancidity,  and  while  some  of  the  substitutes  offered 
in  its  stead  are  entirely  wholesome,  they  should  never  be 
sold  as  butter  or  used  to  adulterate  it.  Neither  should 
butter  contain  an  excess  of  water  nor  of  casein,  as  its 
food-value,  weight  for  weight,  is  thereby  accordingly 
lessened. 

EGGS. 

Eggs  yield  almost  their  full  weight  of  food  in  a  con- 
centrated and  very  digestible  condition,  and  are  valuable 
on  this  account,  as  well  as  for  their  palatability  and  their 
value  in  the  preparation  of  many  dishes.  Although  con- 
taining practically  no  carbohydrates,  they  have  sufficient 
food-material  in  themselves  for  the  complete  develop- 
ment of  the  living  chick  with  the  aid  of  nothing  external 
except  the  oxygen  which  passes  through  the  shell:  the 
lack  of  the  carbohydrate  element,  ordinarily  one  of  the 
essential  food-principles,  is  supplied  by  the  heat  from 
the  mother  hen  or  incubator  which  is  sufficient  for  the 
development  and  maintenance  of  the  vital  processes,  since 
the  unhatched  creature  wastes  almost  no  energy  in  physical 
activity. 

The  white  of  ^gg  is  almost  pure  albumin  with  a  little 
water  and  some  salts;  the  yolk  contains  about  30  per 
cent,  of  fat  and  some  albumin.  The  albumin  coagulates 
at  about  170°  F.,  but  if  it  is  exposed  to  a  still  higher 


264  FOOD 

temperature  for  any  but  a  very  short  period  of  time,  it 
becomes  hard  and  difficult  of  digestion.  A  so-called 
"soft-boiled"  egg  is  scarcely  more  difficult  of  digestion 
than  an  uncooked  one,  and  is  certainly  more  palatable  to 
almost  every  one. 

Eggs,  milk,  and  cheese  may  be  made  into  many  nutri- 
tious and  palatable  combinations  which  furnish  food 
especially  agreeable  to  the  sick,  as  well  as  to  those  whose 
appetite  and  digestive  functions  have  not  been  impaired. 


MEAT. 

Good  meat,  when  deprived  of  its  contained  water,  is 
a  concentrated  food,  and  is  used  not  only  on  account  of 
the  large  amount  of  nutriment  it  contains,  but  also  for 
its  rich  and  agreeable  flavor.  It  represents  much  veg- 
etable matter  converted  into  its  present  palatable  and 
more  digestible  form  by  the  metabolic  activity  of  the 
animals  from  which  it  came.  It  contains  all  the  essential 
food-principles,  the  carbohydrates,  however,  being  present 
as  muscle-sugar  or  inosite  and,  as  in  milk,  in  very  small 
proportion.  In  all  fresh  meat  there  is  much  water,  but 
more  in  lean  than  in  fat  meat;  fat  bacon  contains  60  per 
cent.;  lean  beef,  from  75  to  78  per  cent,  of  water.  As  the 
proportion  of  fat  increases,  the  quantity  of  albuminoids 
or  proteids  decreases :  thus,  lean  beef  may  have  only  2  per 
cent,  of  fat  to  from  20  to  24  per  cent,  of  proteids,  while 
bacon  has  about  24  per  cent,  of  fat  to  15  per  cent,  of 
proteids. 

Of  the  varieties  of  meat  commonly  used,  beef  is  the 
most  nutritious.  Good  beef  should  not  be  too  pale  nor 
too  dark,  should  show  no  blood-clots,  have  almost  no  odor, 
be  elastic  and  not  soggy  to  the  touch,  be  well  marbled 
with  clean,  white  fat,  and  have  compact  flesh.  Dark 
beef  indicates  that  the  animal  was  not  properly  bled,  or 
has  had  some  febrile  disease;  wet  and  flabby  meat,  that 
it  is  approaching  decomposition.     The  flesh   of  young 


RELATION  OF  MEAT  TO  DISEASE  265 

animals  is  more  tender  than  that  of  older  ones,  but  not 
so  digestible,  partly  because  the  young  flesh  cannot  be  so 
thoroughly  masticated  and  the  fibres  so  well  separated. 
Therefore,  veal  is  not  so  digestible  as  beef,  nor  lamb  as 
mutton.  "Young  flesh  is  less  stimulating  and  nutritious 
and  more  gelatinous  than  that  of  the  adult."  (Vaughan.) 
Veal  should  not  be  too  pale,  as  that  indicates  antemortem 
bleeding  or  too  young  an  animal.  The  calf  should  be  at 
least  one  month  old  before  the  killing. 

Mutton  is  more  digestible  than  beef,  but  not  so  nutri- 
tious. Its  flavor  is  objectionable  to  some.  Pork  is  an 
economical  food  for  the  poor  man,  as  pigs  of  good  stock 
store  up  three  times  as  much  of  the  food  they  eat  as  does 
the  ox.  The  flesh  is  also  easily  preserved  by  drying  or 
smoking,  and  ham  and  bacon  are  exceptions  to  the  rule 
that  dried  meats  are  more  indigestible  than  fresh  ones. 
Again,  pork  fat  furnishes  much  heat  for  cold  weather  by 
its  oxidation  and  combustion  in  the  body.  But  it  must  be 
remembered  that  it  requires  good  digestive  power  to  dis- 
pose of  it,  and  that  much  pork  is  not  to  be  advised  for 
those  of  sedentary  habits;  also  that  certain  parasites  are 
especially  liable  to  infest  the  tissues  of  the  pig  and  to  be 
transmitted  thence  to  man. 

The  flesh  of  poultry  is  acceptable  to  most  palates,  if  not 
too  old  and  tough.  White  meat  is  more  digestible  than 
the  dark,  but  not  so  nutritious  or  rich  in  flavor,  since  the 
latter  is  more  highly  nitrogenous.  Chicken  broth  is  more 
nutritious  and  more  laxative  than  that  made  from  mutton. 

Fish  is  not  sufficiently  stimulating  to  constitute  the 
chief  flesh  diet  of  a  people,  but  it  furnishes  variety,  and 
on  account  of  its  contained  phosphorus  should  be  used 
largely  by  those  subject  to  neurosal  affections.  White- 
meated  fish  are  more  delicate  in  flavor  and  more  easily 
digested,  but  not  so  stimulating  as  those  of  red  flesh. 
Some  fish  are  poisonous,  either  by  nature  or  from  inhabit- 
ing foul  waters;  while  any  fish  may  become  so  if  under- 
going decomposition.  Shell-fish  are  particularly  liable 
to  develop  poisonous  ptomains  in  the  process  of  decom- 


266  FOOD 

position,  and,  consequently,  only  such  as  are  absolutely 
fresh  should  be  used. 

Oysters  and  clams  which  have  been  taken  from  a  water 
contaminated  by  sewage  may  also  convey  the  germs  of 
infectious  diseases,  such  as  typhoid  fever;  an  instance  of 
this  having  been  demonstrated  in  the  investigation  of  an 
epidemic  of  the  latter  disease  in  Connecticut,  which  was 
reported  by  Prof.  Conn,  of  Wesleyan  University,  and 
another  in  a  similar  epidemic  at  Atlantic  City,  N.  J., 
in  1903. 

"The  following  meats  should  not  be  eaten:  (1)  The 
flesh  of  all  animals  dead  of  internal  diseases,  or  which 
have  been  killed  while  suffering  from  such  diseases,  or 
animals  killed  by  overdriving.  (2)  The  flesh  of  animals 
with  contagious  diseases  that  may  be  transmitted  to  man. 
(3)  The  flesh  of  animals  that  have  been  poisoned.  (4)  The 
flesh  of  animals  with  severe  infectious  diseases,  as  pyemia, 
etc.  (5)  Flesh  that  contains  parasites  that  may  be  trans- 
mitted to  man.    (6)  All  putrid  flesh. "^ 

Competent  inspectors  are  appointed  by  governmental 
and  state  authorities  to  examine  the  various  meats  offered 
for  sale  in  large  cities,  and  undoubtedly  do  much  good  in 
preventing  the  sale  of  meat  that  is  unfit  for  use.  Unfor- 
tunately, from  false  ideas  of  economy  in  many  communi- 
ties, the  authorized  inspectors  have  been  too  few  in 
number. to  be  able  to  attend  to  all  the  work  that  should 
be  done  by  them. 

Coplin  and  Bevan  give  the  following  as  diseases  which 
are  to  be  specially  guarded  against:  In  cattle,  epidemic 
pleuropneumonia,  foot-and-mouth  disease,  contagious 
typhus,  anthrax,  tuberculosis,  actinomycosis,  Texas  fever, 
dropsical  affections,  and  indigestion.  In  sheep,  braxy, 
variola  ovina,  black  quarter,  phthisis,  fluke  disease,  and 
gid.  In  swine,  anthrax,  hog  cholera,  measles,  and  trichini- 
asis.2  It  should  also  be  remembered  that  the  intestinal 
parasites,  such  as  tape-worms  and  round-worms,  often,  if 

1  Gerlach. 

2  Manual  of  Practical  Hygiene,  1st  edition,  p.  132  et  seq. 


THE  COOKING  OF  MEAT  267 

not  usually,  gain  entrance  into  the  system  through  the 
ingestion  of  meat  containing  them  in  their  embryonal  or 
larval  stages. 

Therefore,  in  cooking  meat,  every  part  should  be  heated 
to  at  least  160°  F.  sufficiently  long  to  destroy  any  disease 
germs  or  parasites  it  may  contain,  as  very  rare  meat  may 
still  harbor  these  organisms  in  a  living  state.  Tubercu- 
losis, for  instance,  may  be  incurred  by  eating  flesh  imper- 
fectly cooked,  since  its  germs  are  quite  resistant;  though  it 
must  be  said  that  this  disease  is  not  so  likely  to  affect  the 
muscular  tissues  of  an  animal  as  are  others  of  the  maladies 
mentioned.  The  development  of  ptomains  in  flesh  may 
also  make  it  quite  poisonous,  and  this  is  especially  likely 
to  take  place  in  meats  that  have  been  kept  for  a  long  time 
after  killing  or  in  those  preserved  in  cans  or  other  packages 
that  have  been  imperfectly  heated  or  sealed. 

Meat  is  also  cooked  to  improve  it  in  appearance  and  to 
make  it  more  agreeable  to  the  palate  and  to  aid  digestion. 
As  already  stated,  the  effect  of  cooking  upon  muscle-tissue 
is  "  to  loosen  the  bundles  of  fibrillse  from  each  other  so  that 
they  are  readily  torn  asunder  or  crushed  by  the  teeth." 
Perfectly  cooked  flesh  is  more  savory  than  that  which  is 
either  underdone  or  overdone.  Meat  cooked  before  rigor 
mortis  sets  in  may  be  tender;  cooked  during  the  rigor,  it 
is  tough  and  is  masticated  with  difficulty;  after  the  rigor 
it  is  more  likely  to  be  tender  when  cooked  than  at  any 
previous  time. 

In  cooking  meat,  the  ultimate  condition  in  which  we 
wish  it  to  be  should  always  be  kept  in  mind,  and  pains 
should  also  be  taken  not  to  overcook  or  use  too  high  a 
temperature.  The  processes  pursued  in  making  a  palat- 
able soup  or  broth,  and  in  cooking  meat  so  that  it  may 
retain  all  its  juices,  salts,  and  flavors,  are  radically  dif- 
ferent. In  the  first  case,  it  is  desired  to  extract  as  much  of 
the  soluble  constituents  of  the  flesh  as  possible,  and  to  do 
this  the  meat  should  be  cut  into  small  pieces  and  allowed 
to  remain  for  a  time  in  cold  water,  this  afterward  being 
very  gradually  raised  to  a  temperature  of  about  160°  F. 


268  FOOD 

In  this  way  the  juices  exude  and  the  salts  and  soluble 
parts  of  the  meat  are  dissolved  before  the  pores  are  closed 
by  the  coagulation  of  the  albumin.  On  the  other  hand, 
if  it  is  desired  to  retain  the  juices  and  savor  in  the  meat, 
the  piece  should  be  as  large  as  possible  that  the  surface 
exposed  will  be  small  in  proportion  to  the  volume.  The 
meat  is  to  be  first  subjected  to  a  temperature  as  high  as 
possible  that  the  surface  may  be  cooked  at  once  and  the 
albumin  coagulated,  the  juices  being  thus  prevented 
from  escaping  by  the  sealing  of  the  pores.  In  boiling, 
this  end  is  attained  by  plunging  the  meat  at  once  into 
boiling  water;  in  roasting,  by  having  the  fire  or  oven  very 
hot.  After  this  first  heating  it  is  best  to  lessen  the  degree 
of  heat  somewhat,  that  the  subsequent  cooking  of  the 
interior  may  go  on  more  slowly  and  the  temperature 
within  may  not  rise  above  the  coagulating-point  and  make 
the  fibres  hard  and  stringy.  Meat  cooked  in  this  way 
should  be  tender,  juicy,  and  rich  in  flavor.  Broiling  or 
grilling  is,  of  course,  but  a  modified  roasting. 

Soups  and  broths  made  of  meat-juices  alone  and  with- 
out the  addition  of  other  substances  are  stimulating  rather 
than  nutritious,  as  they  contain  little  albumin,  carbo- 
hydrates, or  fat.  However,  if  certain  vegetables  be  added 
to  the  soup,  the  latter  will  gain  sufficient  of  these  food- 
principles  and  be  highly  nutritious  and  such  vegetable 
soups  are  of  great  value  in  all  schemes  of  economic  cook- 
ing. Bones  are  also  of  value  on  account  of  the  salts, 
gelatin,  and  other  soluble  organic  matter  which  they  con- 
tain, and  used  with  vegetables  they  make  especially  nutri- 
tious and  easily  digested  soups. 

The  meat  from  which  soup  has  been  made,  on  the  other 
hand,  is  not  all  that  is  desirable,  for  though  it  still  con- 
tains albumin  and  fat,  it  has  lost  its  salts  and  savoriness 
and  is  unpalatable,  and  therefore  not  easily  digested.  It 
needs  something — a  sauce  or  condiment,  or  preferably  a 
meat-extract,  for  meat-extracts  are  nothing  but  thin  soups 
evaporated  to  dryness  or  condensed.  Or,  if  both  soup 
and  the  meat  be  taken  at  the  same  meal,  the  things 


CEREALS  269 

lacking  in  each  are  supplied  by  the  other,  and  the  needs  of 
digestion  and  nutrition  are  supplied. 

Frying  meat,  as  it  is  commonly  practised,  should  not 
be  tolerated,  as  it  renders  the  albumin  of  the  flesh 
extremely  tough,  besides  soaking  it  with  fat  or  grease  and 
thus  greatly  increasing  the  difficulty  of  its  digestion. 
But  frying  by  total  immersion  in  boiling  fat  is  an  excel- 
lent way  of  cooking  meats  containing  much  water,  and 
especially  fish,  for  the  boiling-point  of  fat  or  oil  is  very 
high  and  the  meat  is  instantly  cooked  on  the  outside, 
while*  the  water  in  the  interior,  being  converted  into 
steam,  prevents  the  ingress  of  fat  by  its  expansion,  cooks 
the  albumin,  and  leaves  the  flesh  in  a  light,  flaky  condi- 
tion. But  the  fat  must  be  boiling  hot  when  the  meat  is 
immersed,  and  the  latter  should  not  be  allowed  to  remain 
in  the  former  longer  than  lust  suffices  for  perfect  cooking. 

Beef-tea  as  ordinarily  made  is  only  a  thin  extract  of 
beef,  the  stimulating  properties  of  which  will  be  consid- 
ered hereafter.  To  make  a  beef-tea  containing  any  con- 
siderable amount  of  nutriment,  the  meat  from  which  the 
juices  have  been  extracted  should  be  dried,  pounded  fine, 
and  all  fibrous  and  tendinous  portions  removed.  This 
pounded  beef  should  then  be  added  to  the  liquid  extract, 
as  then  only  is  it  really  a  food.  Moreover,  the  mixture 
should  always  be  seasoned,  even  for  the  sick,  that  it  may 
be  thoroughly  acceptable  to  both  palate  and  stomach. 
In  making  the  extract,  it  should  be  remembered  that  the 
meat  should  be  cut  into  very  small  pieces  and  added  to 
cold  water  in  about  the  proportion  of  one  pound  of  lean 
meat  to  one  pint  of  water,  and  that  the  whole  should  be 
brought  to  the  boiling-point  very  slowly. 

CEREALS. 

The  cereals  form  one  of  the  most  valuable  kinds  of 
food.  All  but  rice  contain  considerable  proteid  matter — 
from  10  to  20  per  cent. — beside  carbohydrates,  which 
predominate,  some  fat,  and  a  goodly  proportion  of  phos- 


270  FOOD 

phates.  Rice  has  only  5  per  cent,  of  proteids  to  75  per 
cent,  of  starch,  but  it  is  easily  digested,  and  is  therefore 
a  valuable  food  for  the  young  and  the  sick;  it  is  also 
well  fitted  as  a  chief  food  for  dwellers  in  hot  climates  on 
account  of  its  low  heat-production. 

Wheat  is  the  most  nutritious  cereal,  and  bread  made 
from  it  is  aptly  called  "the  staff  of  life,"  since  it  is  a 
food  which,  with  the  addition  of  a  little  extra  fat  and 
albumin,  furnishes  the  essentials  in  proper  proportion  for 
the  support  of  life.  Barley  closely  resembles  wheat  in 
composition,  and  rye  also  is  rich  in  nutriment,  though 
perhaps  a  little  more  difficult  of  digestion  than  wheat. 
Oats  are  valuable  on  account  of  the  large  amount  of  fat 
they  contain — over  5  per  cent. — beside  a  full  share  of 
proteids,  starch,  and  salts.  But  ordinary  oatmeal  needs 
vigorous  digestive  functions,  and  where  the  latter  are 
lacking  it  is  often  productive  of  intestinal  disturbance 
and  irritation.  Corn  or  maize,  thoilgh  not  a  true  cereal, 
furnishes  a  valuable  food  with  considerable  fat;  it  also 
contains  a  vegetable  fibrin.  The  proteid  constituents  of 
the  cereals  are  vegetable  albumin,  casein,  and  gluten,  the 
last  of  these  being  most  abundant  in  wheat  and  perhaps 
of  the  highest  food-value. 

Grinding  breaks  up  the  grain  and  the  starch  granules 
of  the  cereals,  aids  in  separating  indigestible  parts,  and 
renders  the  starch  much  more  suitable  for  cooking. 
Wheat  flour  ground  by  the  old  method  should  be  soft  and 
smooth,  but  that  made  by  the  new  roller-process  is  more 
apt  to  be  slightly  granular.  It  should  not  be  too  white, 
as  that  indicates  a  lack  of  the  proper  proportion  of  gluten, 
and  should  contain  everything  but  the  outer  husk  of  the 
grain.  The  inner  coats  should  be  retained  in  the  flour, 
as  they  hold  a  considerable  part  of  the  gluten  and  practi- 
cally all  of  the  grain  salts  and  possibly  the  vitamines.^ 
Cornmeal  should  be  dry  and  powdery,  or  at  least  not  too 

1  The  influence  of  polished  rice  as  a  factor  in  the  causation  of  the  dis- 
ease beriberi  has  been  shown  to  be  due  to  the  loss  of  the  vitamines  in  the 
germ  and  outer  coating  of  the  rice  grains. 


CEREALS  271 

granular.  Flour  of  any  kind  should  be  kept  well  covered 
in  a  dry  place,  and  should  contain  no  living  organisms 
nor  any  adulterants. 

Bread  is  practically  made  of  flour,  water,  and  salt, 
though  sugar,  milk,  etc.,  may  be  added  to  improve  the 
flavor.  As  flour  and  water  alone  make  a  tough  and  indi- 
gestible mass,  bread  is  leavened  to  make  it  easier  of  mas- 
tication and  digestion,  and  for  this  purpose  either  yeast, 
baking-powder,  or  aeration  is  employed.  Yeast  at  the 
proper  temperature  rapidly  converts  some  of  the  starch 
or  sugar  into  carbon  dioxide  and  alcohol,  the  former  of 
which  in  escaping  makes  the  dough  porous  and  light,  the 
walls  of  the  cavities  it  produces  being  kept  from  collaps- 
ing by  the  tenacity  of  the  gluten  until  the  heat  fixes  them 
permanently.  As  the  heat  of  baking  dissipates  both  the 
gas  and  alcohol,  from  10  to  12  per  cent,  of  the  weight  of 
the  flour  used  is  lost  by  this  method.  Moreover,  if  the 
fermentation  goes  beyond  a  certain  point,  lactic  and  acetic 
acids  are  formed  and  the  bread  becomes  "sour."  Con- 
sequently, it  has  been  advised  that  the  yeast  method  be 
discarded,  and  that  the  leavening  be  done  by  means  of 
baking-powders  or  aeration.  Carbon  dioxide  is  evolved 
from  the  baking-powders  upon  the  application  of  heat  and 
moisture,  and  the  bread  is  made  light  by  the  gas,  with  no 
loss  of  food-substance,  and,  if  the  powders  are  pure,  with 
nothing  harmful  added  to  the  bread.  There  should  be 
no  alum  or  other  adulterants  in  baking-powders  nor 
in  the  flour  itself.  Alum  unites  with  the  phosphates 
of  the  flour,  rendering  them  insoluble  and  preventing 
their  absorption  from  the  alimentary  tract.  Bread  may 
also  be  leavened  on  a  large  scale  by  forcing  air  or  carbon 
dioxide  under  high  pressure  into  the  dough,  or  by  mixing 
the  flour  with  cold  water  heavily  charged  with  the  latter 
gas.  In  this  method,  also,  there  can  be  no  loss  of  food- 
material  nor  any  detriment  to  the  bread,  provided  cleanly 
precautions  are  observed. 

Good  wheat  bread  should  be  almost  white,  light,  sweet, 
spongy,  and  with  a  crust  easily  broken  and  equal  in  bulk 


272  .         FOOD 

to  about  one-quarter  of  the  loaf.  As  considerable  of  the 
starch  has  been  converted  into  dextrine  in  the  crust,  the 
latter  is  more  easily  digested  than  the  interior  of  the  loaf. 
Fresh  bread  is  not  nearly  so  digestible  as  that  which  is 
a  day  or  two  old.  As  stated,  bread  needs  only  a  little 
added  fat  and  albumin  to  make  it  a  perfect  food,  the 
former  of  which,  at  least,  is  almost  if  not  quite  sufficiently 
supplied  in  the  butter  which  is  commonly  used  upon  it. 

VEGETABLES. 

The  vegetables  in  common  use  are  valuable  articles 
of  food  in  that  they  give  us  the  larger  portion  of  carbohy- 
drates and  also  furnish  an  agreeable  variety  from  day  to 
day.  In  the  fresh  state  they  contain  considerable  water — 
from  75  to  90  or  95  per  cent. — the  residue  being  mainly 
one  or  another  of  the  carbohydrates.  Potatoes  exemplify 
this  well,  since  they  contain  but  little  proteids  and  fat, 
and  practically  all  of  their  solid  matter  is  starch.  On 
account  of  their  customary  cheapness  and  ease  of  growth 
and  storage  they  are  usually  considered  to  be  a  valuable 
article  of  food  for  the  poor  man,  but  it  should  not  be  for- 
gotten that  other  foods  which  are  apparently  more  expen- 
sive may  at  times  be  actually  cheaper  than  potatoes, 
both  on  account  of  containing  those  principles  which  the 
latter  lack  and  because  they  require  less  expenditure  of 
digestive  energy.  (See  chart,  page  276.)  Beets  contain 
much  sugar  and  are  nutritious,  palatable,  and  easily 
digested.  Onions  have  considerable  sulphur,  and  should 
be  used  freely  when  its  need  is  indicated.  Cabbage,  cress 
and  other  greens  are  especially  valuable  for  the  organic 
salts  which  they  contain,  and  because  they  serve  so  well 
as  relishes.  Spinach  is  said  to  contain  more  assimilable 
iron  than  any  other  article  of  food  commonly  used.  Celery 
and  lettuce  are  nerve  sedatives,  and  asparagus  acts  as  a 
diuretic  and  is  thought  to  be  of  special  benefit  to  the 
kidneys. 

A  caution  should  be  introduced  here  concerning  the 


VEGETABLES  273 

use  of  raw  vegetables  which  may  carry  from  the  soil  the 
germs  of  certain  infectious  diseases  derived  from  the 
fertihzers  used  in  the  field  or  from  other  sources.  There 
can  be  no  doubt  that  these  have  been  the  cause  of  infec- 
tion in  certain  cases,  as  of  typhoid  fever,  and  Metchnikoff 
has  pointed  out  that  while  such  germs  are  probably  de- 
stroyed by  the  normal  bacteria  and  reactions  of  the  diges- 
tive tract,  an  abnormal  condition  of  the  latter  may  permit 
their  introduction  and  the  development  of  their  specific 
maladies. 

The  seeds  of  the  leguminous  group  of  plants,  such  as 
peas,  beans,  lentils,  etc.,  contain  from  22  to  25  per  cent, 
of  proteid  matter  in  the  form  of  vegetable  casein,  and 
almost  50  per  cent,  of  starch.  It  is  on  account  of  this 
abundance  of  food-matter  that  they  make  such  a  valuable 
addition  to  soups  and  the  like,  and  for  the  same  reason 
they  should  also  be  used  in  any  dietary  where  economy 
of  expense  is  a  factor.  Green  peas  and  beans  are  much 
more  digestible  than  those  that  have  ripened  and  dried, 
though,  of  course,  they  do  not  yield  so  much  nutriment, 
weight  for  weight,  as  the  latter. 

All  vegetables  should  be  so  cooked  as  to  retain  their 
salts,  or  else  the  water  in  which  they  are  cooked  and 
which  contains  these  salts  should  be  used  in  making  soup 
or  broth,  to  be  served  at  the  same  meal  with  the  vege- 
tables. This  is  especially  advisable  with  regard  to  pota- 
toes and  sweet  potatoes,  as  their  soluble  salts  have  much 
to  do  with  their  digestibility.  It  is  for  this  reason  that 
a  properly  roasted  potato  is  always  better  than  a  boiled 
one,  and  that  steamed  vegetables  are  both  more  palatable 
and  more  digestible  than  those  which  have  been  cooked 
under  water.  In  fact,  Mattieu  Williams  has  even  sug- 
gested that  possibly  one  reason  why  gout  is  so  prevalent 
among  Englishmen  is  because  they  habitually  eat  boiled 
vegetables  and  throw  away  the  water  in  which  these  have 
been  cooked.  The  salts  not  only  help  in  the  digestion  of 
the  starches,  but  they  furnish  bases  to  unite  with  and 
render  soluble  the  irritating  acids  that  produce  the  gouty 
18 


274  FOOD 

symptoms.  It  should  also  be  remembered  that  the  dried 
legumes  should  always  be  softened  by  soaking  in  water 
before  cooking,  and  that  they  as  well  as  other  vegetables 
should  be  cooked,  whenever  possible,  in  soft  water. 

Prepared  starches,  such  as  arrow-root,  tapioca,  sago, 
etc.,  are  easily  digestible,  and  therefore  useful  especially 
in  the  preparation  of  food  for  the  young  and  the  sick. 

Fruits  are  especially  valuable  on  account  of  their 
flavor,  acceptability  to  the  palate,  benefit  to  the  diges- 
tion, and  for  their  laxative  action.  Ripe  fruits  may  be 
eaten  freely:  in  most  cases  preferably  early  in  the  day. 
Fresh  fruits  are  usually  better  than  those  dried  or  other- 
wise preserved;  but  where  the  former  cannot  be  had,  the 
latter  should  be  used  freely,  and  all  should  be  used 
throughout  the  year  whenever  possible.  For  obvious 
reasons,  green  fruit,  or  that  which  has  begun  to  decay, 
should  not  be  eaten. 

Nuts  are  nutritious  on  account  of  the  high  percentage 
of  fat  that  most  of  them  contain,  but  are  difficult  of  diges- 
tion unless  thoroughly  masticated.  Recently  pastes  made 
from  various  nuts  have  been  placed  on  the  market,  and 
are  to  be  considered  as  an  agreeable  addition  to  our 
dietaries. 

ADULTERANTS  AND  PRESERVATIVES. 

Much  might  be  written  concerning  the  adulteration 
and  sophistication  of  foodstuffs  and  of  the  addition  of 
more  or  less  harmful  preservatives  to  food  of  a  perishable 
nature.  That  the  first  is  carried  on  to  an  enormous  extent 
seems  certain.  The  remedy  appears  to  be  in  the  passage 
and  enforcement  of  stringent  laws  and  the  maintenance 
of  frequent  and  rigid  inspection  by  both  state  and  govern- 
mental authorities,  in  the  dissemination  of  information 
as  to  the  adulterations  practised  and  the  means  of  detect- 
ing them,  and  in  the  utmost  publicity  and  exposure  in 
the  case  of  transgressors,  all  of  which  is  now  being  effected 
by  the  provisions  of  the  Pure  Food  and  Drugs  Act 
and  the  means  employed  for  its  enforcement. 


ADULTERANTS  AND  PRESERVATIVES         275 

This  law,  which  became  effective  on  January  1,  1907, 
provides  "That  for  the  purposes  of  the  act,  an  article 
shall  be  deemed  to  be  adulterated  in  the  case  of  food: 
First.  If  any  substance  has  been  mixed  and  packed  with 
it  so  as  to  reduce,  or  lower,  or  injuriously  affect  its  quality 
or  strength.  Second.  If  any  substance  has  been  substi- 
tuted wholly  or  in  part  for  the  article.  Third.  If  any 
valuable  constituent  of  the  article  has  been  wholly  or  in 
part  abstracted.  Fourth.  If  it  be  mixed,  colored,  pow- 
dered, coated,  or  stained  in  a  manner  whereby  damage  or 
inferiority  is  concealed.  Fifth.  If  it  contain  any  added 
poisonous  or  other  added  deleterious  ingredient  which  may 
render  such  article  injurious  to  health.  Sixth.  If  it  con- 
sists in  whole  or  in  part  of  a  filthy,  decomposed,  or  putrid 
animal  or  vegetable  substance  or  any  portion  of  an  animal 
unfit  for  food,  whether  manufactured  or  not,  or  if  it  is  the 
product  of  a  diseased  animal,  or  one  that  has  died  other- 
wise than  by  slaughter." 

As  to  the  use  of  preservatives,  the  very  extensive  sale, 
heretofore,  of  these  in  localities  where  they  would  be  most 
likely  to  be  added  to  food  indicates  their  employment,  as 
does  their  continual  discovery  by  direct  analysis.  In  Bir- 
mingham, England,  such  preservatives  were  found  in  20 
per  cent,  of  2300  samples  of  food  examined,  and  boric  acid 
in  5  per  cent,  of  1360  samples  of  milk.  Such  substances  as 
boric  acid,  salicylic  acid,  and  formaldehyde  are  commonly 
used,  though  it  is  frequently  stated  that  more  dangerous 
ones,  such  as  hydrofluoric  acid,  are  occasionally  employed. 
And  though  it  should  in  fairness  be  stated  that  it  is  pos- 
sible that,  if  only  the  minimum  of  such  substances  as  boric 
acid  and  formaldehyde  necessary  to  prevent  putrefactive 
or  fermentative  changes  in  food  be  used,  no  harm  to  the 
human  economy  will  result,^  yet  it  is  undoubtedly  wiser 

» Rideal  and  Fullerton  (Public  Health,  May,  1899)  arrive  at  the 
following  conclusions:  (1)  Boric  acid  (1  to  2000)  and  formaldehyde 
(1  to  50,000)  are  effective  preservatives  for  milk  for  twenty- four  hours. 
(2)  These  quantities  have  no  appreciable  effect  upon  the  digestion.  (3) 
These  quantities  have  no  appreciable  effect  upon  the  digestibility  of 
foods  prepared  with  them.  (4)  Formaldehyde  in  the  proportion  given 
above,  so  far  as  their  investigations  have  extended,  does  not  appear  to 
have  any  injurious  action  upon  animal  tissues  or  nutrition. 


276 


FOOD 


to  condemn  the  practise  of  adding  chemical  preservatives 
of  any  kind  to  food.  There  are  two  reasons  for  this: 
(1)  There  is  no  surety  and  very  Httle  probabiHty  that  the 
minimum  quantity  of  preservative  consistent  with  safety 
to  health  will  not  be  exceeded  in  most  cases  through  care- 
lessness or  recklessness.  (2)  That  foods  that  apparently 
require  such  preservatives  should  be  supplied  to  the 
consumer  before  the  deterioration  in  them  has  begun,  or 
else  they  should  be  sterilized  by  the  more  costly  but  safer 
employment  of  heat. 

The  following  diagram  may  be  of  service  in  deter- 
mining the  value  of  certain  foodstuffs. 


Fig.  78 


CHAPTER  VII. 

STIMULANTS  AND  BEVERAGES. 

The  essential  function  and  property  of  stimulants  is  to 
liberate  some  of  the  latent  force  of  the  body ;  hence  they  are 
of  use  and  value  in  sudden  emergencies,  to  tide  the  system 
over  important  crises,  to  hasten  a  tardy  convalescence,  or 
perchance  to  whip  up  a  flagging  digestion  so  that  it  may 
more  thoroughly  prepare  food  for  the  repair  of  waste  or 
the  supplying  of  body-fuel.  Those  stimulants,  excluding 
drugs,  with  which  we  are  most  concerned  are  of  three 
classes,  viz.,  nitrogenized  vegetable  stimulants,  such  as 
tea  and  coffee;  nitrogenized  animal  stimulants,  as  beef- 
tea  and  meat-extracts;  and  alcohol.  All  these  are  "force- 
liberators,"  and  though  alcohol  may  sometimes  act  the 
part,  in  more  moderate  measure,  of  a  "force-producer," 
it  is  well  to  remember  that  they  give  scarcely  anything 
at  all  to  renew  or  replace  the  energy  which  they  set  free. 
This  being  so,  care  should  always  be  taken  that  some 
food  be  supplied  during  or  shortly  after  the  stimulation 
produced  by  the  agents  in  question,  in  order  that  the 
body  may  have  a  new  store  of  force  to  replace  that  which 
has  been  liberated.  Especially  is  this  necessary  in  cases 
of  sickness;  and  as  the  soluble  carbohydrates  furnish  fuel 
and  consequent  heat  and  energy  to  carry  on  the  vital  pro- 
cesses, these  even  more  than  other  kinds  of  food  are  to  be 
supplied,  and  will  generally  be  well  received  and  utilized 
by  patients  or  others  in  need  of  stimulation.  Again,  just 
as  we  must  not  depend  on  stimulants  alone  to  the  exclu- 
sion of  food,  so  also  must  we  take  care  not  to  continue 
their  use  any  longer  than  is  necessary  to  attain  our  object, 
and  likewise  must  not  overstimulate  or  carry  the  action 

(277) 


278  STIMULANTS  AND  BEVERAGES 

so  far  that  the  body  is  left  poorer  and  weaker  in  force 
than  before  the  use  of  the  stimulants  began. 

For  example,  beef-tea  constantly  stimulates  the  vital 
and  nervous  functions  to  greater  activity,  this  requiring 
that  either  tissue  or  food  be  oxidized  to  produce  the  neces- 
sary energy.  The  stimulating  factors  in  ordinary  beef-tea 
are  the  meat-extractives,  such  as  kreatin  and  kreatinin, 
which  are  products  of  the  wear  and  tear  of  life,  inter- 
mediate between  living,  active  tissue  and  the  final  excre- 
tory mattei's,  such  as  urea  and  uric  acid;  hence  they  can 
have  little,  if  any,  real  food-value.  Beside  these  the  beef- 
tea  contains  only  the  salts  of  the  meat,  which,  though  valu- 
able, are  not  force-producers.  Therefore,  unless  food  be 
otherwise  supplied,  the  body  tissue  must  be  consumed, 
and  the  result  must  eventually  be  disastrous;  and  yet 
this  is  what  occurs  to  many  patients  through  the  mis- 
taken idea  that  beef-tea  is  both  nourishing  and  stimu- 
lating. When  "whole  beef-tea"  (the  recipe  for  which  is 
given  on  page  269)  is  used,  these  remarks  do  not  apply, 
since  it  contains  some  true  food,  though  even  here  soluble 
or  readily  digestible  carbohydrates  may  wisely  be  added. 

The  active  principles  of  the  nitrogenized  vegetable 
stimulants  resemble  very  closely  in  chemical  composi- 
tion not  only  the  meat-extractives,  but  also  those  drugs, 
like  strychnine,  which  are  used  in  medicine  as  tonics  and 
cerebrospinal  stimulants,  and  they  act  physiologically  in 
a  similar  though  milder  manner. 

As  beverages,  tea,  coffee,  and  cocoa  supply  fluid  for  the 
system  and  that  stimulation  of  the  assimilative  functions 
that  causes  a  sense  of  comfort  after  their  use,  cocoa  and 
chocolate  having  also  the  advantage  of  supplying  some 
food.  But  these  beverages  may  all  be  abused  in  their  use 
as  readity  as  may  beef-tea  or  alcohol,  and  "tea-drunkards" 
and  "coffee-drunkards"  are  not  uncommon  in  hospitals 
and  in  private  life.  The  teacup  is  not  always  the  one 
that  "cheers  but  does  not  inebriate."  Women  especially 
who  drink  much  tea  are  apt  to  be  nervous  and  dyspeptic, 
to  have  the   "tea-drinker's  heart,"  and  to  suffer  from 


ALCOHOL  279 

headaches  and  neuralgias.  They  depend  upon  tea  to  take 
the  place  of  nutriment,  and  soon  use  up  what  little  store 
of  force  they  may  have  had,  since  they  fail  to  replenish  it 
with  fuel-food.  Men  are  more  addicted  to  the  use  and 
abuse  of  coffee,  and  often  manifest  symptoms  directly 
traceable  to  such  intemperance.  While  caffeine  increases 
heart  action,  and  may  be  used  to  advantage  in  cases  of 
cardiac  debility,  for  the  same  reason  it  should  be  taken 
with  caution  and  in  moderation  where  the  cardiac 
action  is  already  too  vigorous.  Vogel  has  advised  the 
use  of  strong  coffee  with  sugar  and  cream  as  a  tonic 
and  food  in  debility  accompanying  the  acute  diseases 
of  children. 

It  is  interesting  to  note  that  among  all  nervous,  ener- 
getic people  the  use  of  some  one  or  other  of  these  stimu- 
lant beverages  is  common,  and  that  "total  abstainers" 
from  alcohol  seem  instinctively  to  resort  to  tea  or  coffee. 
And  while  it  is  probably  theoretically  true  that  the 
healthy  person  would  better  abstain  entirely  from  the  use 
of  stimulants,  except  in  emergencies  or  at  rare  intervals, 
yet  the  almost  universal  desire  for  and  use  of  them  prob- 
ably indicate  that  under  our  present  high  tension  of 
living  there  is  a  real  physiological  demand  and  need  for 
them  that  perhaps  should  be  satisfied  in  a  measure,  but 
with  moderation  and  judgment. 

ALCOHOL. 

Liebig  says  that  "alcohol  stands  only  second  to  fat  as 
a  respiratory  material,"  but  adds  that  "the  same  effect 
could  be  produced  in  the  body  by  means  of  saccharine 
and  farinaceous  articles  of  food  at  one-fourth  or  one- 
fifth  the  cost."  Fothergill  also  holds  "that  the  chief 
portion  of  the  alcohol  ingested  undergoes  consumption  in 
the  body,"  but  insists  that  "the  question  of  *  alcohol  as  a 
food'  can  never  be  separated  or  divorced  from  that  of 
'alcohol  as  a  stimulant'  or  as  a  force-liberator." 

Much  undue  importance  has  certain   been  given  to 


280  STIMULANTS  AND  BEVERAGES 

scientific  investigations  that  served  to  establish  the 
fact  that  alcohol  can  be,  and  often  is,  almost  completely 
oxidized  in  the  body,  and  that  it  produces  therein  prac- 
tically the  same  number  of  heat-units  as  when  it  is  con- 
sumed outside.  But  the  inference  that  it  can  therefore 
be  substituted  for,  and  used  with  impunity  in  place  of 
the  usual  carbonaceous  foods  is  not  justifiable,  because 
the  powerful  physiological  and  ultimate  pathological  effect 
of  the  alcohol  upon  the  higher  nerve-centres  and  active 
tissues  is  ignored,  because  of  the  liberation  of  the  body's 
latent  force  in  excess  of  the  energy  which  the  alcohol  sup- 
plies, and  because  even  the  above-mentioned  investiga- 
tions and  experiments  went  to  show  that  there  was  an 
actual  detriment  to  the  nitrogen-bearing  tissues  of  the 
body  during  its  use. 

Again,  Liebig  writes  that  "the  use  of  spirits  is  not  the 
cause  but  the  effect  of  poverty.  It  is  the  exception  to 
the  rule  when  the  well-fed  man  becomes  a  spirit-drinker. 
On  the  other  hand,  when  the  laborer  earns  by  his  work 
less  than  is  required  to  provide  the  amount  of  food  which 
is  indispensable  in  order  to  restore  fully  his  working 
power,  an  unyielding,  inexorable  law  or  necessity  compels 
him  to  have  recourse  to  spirits.  He  must  work;  but  in 
consequence  of  insufficient  food  a  certain  portion  of  his 
working  power  is  daily  wasting.  Spirits,  by  their  action 
on  the  nerves,  enable  him  to  make  up  the  deficient  power 
at  the  expense  of  his  body;  to  consume  today  that  quan- 
tity which  naturally  ought  to  have  been  employed  a  day 
later."  This  may  also  be  the  case  where  there  is  an 
abundance  of  food,  but  where  it  is  improperly  chosen 
for  the  needs  of  the  individual  or  ruined  by  bad  cook- 
ing. Education  in  the  principles  of  the  scientific  and 
economical  selection  of  food  and  its  preparation  may 
thus  become  a  means  of  preventing  those  diseases  that 
depend  on,  or  are  aggravated  by,  insufficient  or  improper 
food  and  consequent  alcoholic  excesses.  The  effect  of 
alcohol  upbn  the  weak  and  savage  races  is  much  more 
marked  and  disastrous  than  upon  the  civilized  and  strong ; 


RULES  GOVERNING  THE  USE  OF  ALCOHOL     281 

so  it  harms  the  health  of  the  underfed  and  overworked 
mucli  more  than  it  does  that  of  the  well-fed  man  of  means 
and  leisure,  and  affects  women  and  children  more  than  adult 
men.     This  latter  point  is  to  be  remembered  in  practice. 

Remember  also  that,  while  alcohol  is  partially  a  respi- 
ratory stimulant,  it  is  a  force-liberator  and  consumes  the 
body-store,  and  unless  given  with  other  readily  oxidizable 
food  the  risk  is  run  of  putting  a  patient  "in  a  grave 
never  dug  by  Nature,"  especially  where  there  is  already 
danger  of  the  patient  sinking  from  exhaustion.  But  it  is 
just  in  these  cases,  when  given  with  other  food,  that  we 
find  alcohol  a  valuable  therapeutic  agent.  Give  it  with 
foods  that  produce  heat  and  force — i.  e.,  some  form  of 
the  soluble  carbohydrates,  as  maltose,  malt-extracts,  milk, 
milk-whey,  or  even  sugar.  Where  the  assimilative  powers 
are  weak  it  may  be  advantageous  or  necessary  partially  or 
wholly  to  predigest  these  foods;  but  above  all,  remember 
to  replace  what  alcohol  takes  from  the  body,  or  physio- 
logical bankruptcy  will  ensue.  Note  also  that,  though 
alcohol  may  be  in  one  sense  a  food,  it  is  a  very  costly  one, 
and  that  intoxication  must  occur  long  before  a  man  could 
get  the  equivalent  of  a  full  meal. 

Alcohol  is  to  be  used  in  sickness  practically  to  sustain 
the  vital  powers,  to  meet  emergencies,  and  to  lift  the 
patient  over  obstructions  in  the  road  to  health;  and  such 
use  requires  a  thorough  knowledge  of  its  action  coupled 
with  the  highest  judgment.  It  should  also  be  noted  that 
there  is  an  increasing  tendency  on  the  part  of  the  medical 
profession  to  prescribe  alcohol  much  less  frequently  and 
more  sparingly  than  was  formerly  the  practice. 

In  malt  liquors  there  is  usually  considerable  maltose, 
thus  combining  with  the  alcohol  a  soluble  carbohydrate 
of  the  highest  value,  and  these  brewed  ales,  etc.,  may  some- 
times be  used  with  benefit  as  tonics,  especially  where  con- 
valescence is  protracted.  The  stronger  distilled  liquors 
are  diffusible  cardiac  stimulants,  and  are  possibly  valu- 
able in  emergencies,  but  the  continued  use  of  them  must 
only  be  advised  with  great  caution. 


282  STIMULANTS  AND  BEVERAGES 

Fothergill  gives  two  excellent  rules  for  the  use  of  alcohol 
by  the  healthy:  "First,  never  have  alcohol  in  the  brain 
when  it  has  work  to  do;  second,  a  little  alcohol  betwixt  a 
a  man  and  past  trouble  is  permissible;  but  it  is  not  well  to 
put  a  little  alcohol  in  front  of  a  coming  trouble."  Murchi- 
son,  in  his  work  on  Fevers,  lays  down  these  rules  for  practice, 
which  it  would  be  well  for  all  to  adopt:  "What  are  the 
conditions  of  the  animal  economy  in  which  alcohol  may  be 
of  positive  use?  That  there  are  such  conditions,  I  believe 
cannot  be  denied  by  anyone  who  has  honestly  studied  the 
subject;  but  they  are  not  the  conditions  of  perfect  health. 
It  is  especially  when  the  circulation  is  weak  or  sluggish 
that  a  daily  allowance  of  alcohol  may  do  good.  Thus:  (1) 
Alcohol  is  useful  in  the  course  of  most  acute  diseases 
when  the  organs  of  circulation  begin  to  fail,  as  they  are 
apt  to  do.  A  moderate  quantity  usually  suffices.  The 
large  quantity  still  sometimes  administered  may  do  harm 
by  inducing  congestion  of  internal  organs.  (2)  In  con- 
valescence from  acute  diseases  or  from  weakening  ail- 
ments, when  the  circulation  remains  feeble  and  the  tem- 
perature is  often  subnormal,  alcohol  is  useful  in  promoting 
the  circulation  and  assisting  the  digestion.  (3)  In  persons 
of  advanced  life  the  circulation  is  also  often  feeble,  and 
a  moderate  allowance  of  alcohol  often  appears  to  be  bene- 
ficial. All  other  conditions  of  the  system  marked  by 
weakness  of  the  muscular  wall  of  the  heart,  whether 
permanent  or  transient,  are  usually  benefited  by  alcohol." 
Alcohol  may  thus  be  of  value  in  forestalling  or  overcom- 
ing the  depressing  influences  of  the  toxins  produced  in 
certain  of  the  infectious  diseases,  and  in  shock.  In  the 
latter,  however,  especially  when  due  to  accident  or  to 
some  sudden  cause,  much  harm  rather  than  good  may  be 
done  by  the  administration  of  excessive  doses  of  alcohol, 
on  account  of  their  effect  upon  the  depressed  vital  centres, 
and  it  is  well  to  remember  that  better  and  speedier  results 
will  probably  follow  small  doses  sufficiently  frequently 
repeated. 

Alcohol  is  a  good  servant,  but  a  bad  master.     King 


MV£!HAGJSS  283 

Chambers  says:  "Let  alcohol  be  taken  never  as  a  stimu- 
lant or  preparative  for  work,  but  as  a  defence  against 
injury  done  by  work,  whether  of  mind  or  body.  For 
example,  it  is  best  taken  with  the  evening  meal  or  after 
toil.  Let  the  increase  in  the  desire  for,  and  the  power  of, 
digesting  food  be  the  guide  and  limit  to  the  consumption 
of  all  alcoholic  liquids.  Let  the  forms  be  such  as  contain 
the  least  proportion  of  fusel  oil.  Let  all  with  an  heredi- 
tary tendency  to  hysteria  or  other  functional  diseases  of 
the  nervous  system  refrain  from  its  use  altogether,  even 
though  as  yet  in  good  health." 

BEVERAGES. 

To  comment  individually  upon  the  multitude  of  non- 
alcoholic and  non-stimulating  beverages  that  are  now 
more  or  less  generally  used,  is  both  impracticable  and 
unnecessary,  nor  will  any  attempt  to  classify  them  be  of 
much  value.  For  the  most  part  they  serve  only  to  please 
the  palate;  though  if  in  this  way  they  bring  about  a 
greater  ingestion  of  fluids  when  these  are  needed,  their 
service  cannot  be  considered  a  vain  one.  For  it  has  already 
been  stated  that  an  ample  supply  of  drinking-water  or 
other  fluids  taken  daily  and  habitually  is  essential  to  the 
satisfactory  removal  of  the  various  waste  matters  from 
the  body,  and  that  without  it  the  latter  may  readily 
develop  conditions  favoring  disease. 

Moreover,  it  is  true  that  certain  gases  and  salts  held 
in  solution  in  some  beverages,  such  as  mineral  waters, 
increase  this  excretory  action,  and  may  be  highly  bene- 
ficial in  appropriate  cases;  but  it  should  be  a  matter  of 
caution  that  where  such  therapeutic  results  are  thought 
to  be  necessary,  competent  medical  advice  should  be  the 
guide  as  to  the  kind  and  quantity  of  the  agents  used. 
This  comment  is  justified  by  the  fact  that  of  late  many 
substances  capable  of  influencing  the  body  functions  have 
been  advertised  and  sold  in  the  form  of  one  beverage 
or  another  directly  to  the  laity,  who,  being  incompetent 


284  STIMULANTS  AND  BEVERAGES 

to  judge  as  to  whether  or  not  such  substances  are  actually 
needed  in  their  individual  cases,  may  in  this  way  do  them- 
selves much  harm. 

Only  such  beverages,  then,  as  are  quite  simple  in  their 
nature  or  as  are  advised  by  competent  medical  authority 
should  be  used.  If  they  are  artificially  made  and  water 
is  the  solvent  fluid,  as  it  will  be  in  most  cases,  there 
should  also  be  a  certainty  that  it  comes  from  a  clean  and 
safe  source,  lest  it  carry  the  germs  of  disease.  There  is 
no  doubt  that  frequently  the  cheaper  bottled  drinks  which 
are  dispensed  so  generally  are  made  from  water  that  has 
been  liable  to  more  or  less  dangerous  pollution,  and  there 
is  the  additional  risk  that  arises  from  the  imperfect  cleans- 
ing of  the  bottles  for  these  liquids  which  have  been 
returned  to  be  refilled.  A  little  thought  as  to  the  dangers 
which  do  exist  in  relation  to  this  matter  will  be  convinc- 
ing as  to  their  gravity. 

Many  of  the  most  popular  beverages  are  charged  with 
carbon  dioxide  under  compression,  and  the  fact  that  so 
much  of  this  gas  can  be  taken  into  the  system  in  this  way 
without  apparent  harm,  and  its  free  elimination,  would 
seem  to  be  additional  evidence  that  it  cannot  in  itself  be 
so  very  harmful  in  the  atmosphere,  even  when  in  propor- 
tions considerably  greater  than  the  normal. 

In  conclusion,  it  may  be  said  that  a  free  use  of  all  such 
beverages  as  are  known  to  be  clean,  safe,  and  wholesome 
will  probably  be  found  to  be  entirely  favorable  to  health 
unless  there  be  some  contra-indicating  reasons  peculiar  to 
the  individual  himself;  and  that  their  substitution,  when- 
ever possible,  in  place  of  the  alkaloidal  and  alcoholic 
stimulants  is  to  be  commended  on  hygienic  as  well  as 
other  grounds. 


CHAPTER  VIII. 
PERSONAL  HYGIENE. 

The  proper  consideration  of  this  subject  demands  an 
ample  volume  rather  than  the  limits  of  a  single  chapter, 
for  the  ultimate  aim  of  all  sanitary  work  is  the  preserva- 
tion and  betterment  of  the  health  of  the  individual,  and 
beside,  the  factors  that  affect  the  well-being  of  the  person 
are  so  multitudinous  in  their  number  and  in  their  phases 
that  no  brief  discussion  can  comprehend  them  all. 

However,  much  that  pertains  to  personal  hygiene  and 
that  requires  no  repetition  for  its  application  has  already 
been  given  in  the  preceding  pages;  so  that  it  is  hoped 
that  if  the  reader  will  exercise  that  virtue  of  common- 
sense  and  reflection  that  is  so  essential  in  this  study,  the 
remarks  to  be  added  will  be  helpful  in  suggestion  and  in 
answering  many  questions,  even  though  they  may  not 
be  considered  in  any  way  as  complete  discussions  of  the 
respective  themes. 

Each  age  has  its  own  requirements,  and  that  which 
may  be  entirely  satisfactory  or  permissible  at  one  time 
may  not  be  so  at  another.  To  attain  the  best  results  it 
will  often  be  necessary  even  to  anticipate  with  prophyl- 
actic measures  the  birth  of  the  child;  and,  broadly  speak- 
ing, much  of  the  welfare  of  future  generations  lies  in  the 
care  of  those  now  living. 

One  of  the  gravest  sociological  problems  of  the  day  is  as 
to  how  far  the  State  is  justified  in  restricting  or  prevent- 
ing the  propagation  of  the  defective  or  degenerate  of  the 
human  race;  and  though  the  time  may  not  be  ripe  for 
the  law  to  take  positive  action  in  these  matters,  it  is  the 
duty  of  every  sanitarian  to  use  his  utmost  efforts  to  the 
end  that  only  the  healthy  and  the  normal  may  continue. 

(285) 


286  PERSONAL  HYGIENE 

The  advances  in  physiological  and  biological  science  in 
recent  years  have  done  much  for  all  humanity,  but  in  no 
respect,  perhaps,  have  they  been  of  more  service  than  in 
determining  the  great  influences  of  heredity  and  environ- 
ment and  in  establishing  the  fact  that  the  presence  or 
absence  of  disease  is  oftentimes,  if  not  always,  due  as 
much  to  predisposing  conditions  and  the  physical  status  of 
the  individual  as  to  external  and  exciting  causes.  What 
may  cause  only  a  trifling  ill  in  one  may  bring  about  most 
serious  evils  in  another  whose  estate  is  not  so  fortunate. 

Life  has  been  defined  as  the  power  of  an  organism  to 
adjust  continually  its  internal  conditions  to  its  external 
conditions,  and  as  long  as  this  is  satisfactorily  done  life 
persists.  The  secret  of  personal  hygiene  and  health,  then, 
must  lie  in  determining  the  relationship  between  the  in- 
ternal and  external  conditions  of  the  individual's  organism. 

"Know  thyself"  is  advice  good  for  the  body  as  well 
as  for  the  mind  or  soul,  and  knowledge  of  the  right  kind 
can  do  no  harm.  He  who  knows  his  personal  and  physical 
nature  and  acts  accordingly  is  well  equipped  to  fight 
against  the  ills  of  life,  and  the  study  of  the  relationship 
above  referred  to  will  help  the  thinking  man  so  to  care 
for  himself  that  in  all  probability  his  days  will  be  pro- 
longed. 

But  a  caution  or  two  must  be  interpolated  here.  It  is 
well  known  that  "expectant  attention"  too  persistently 
directed  toward  a  particular  organ  may  lead  to  decided 
alterations  or  disturbances  in  the  functions  of  that  organ; 
and  again,  unless  one  well  understands  the  mysteries  of 
human  physiology,  a  little  imperfect  or  insufficient  infor- 
mation in  this  respect  may  lead  to  the  assumption  or  pur- 
suit of  habits  and  practises  actually  dangerous  to  health. 
Too  much  ill-advised  care  and  attention  may  be  just  as 
full  of  risk  as  too  little,  and  physiological  egotism  without 
a  sound  basis  may  have  a  bitter  reward. 

What  is  needed  is  that  each  one  should  study  care- 
fully the  phenomena  of  his  daily  life,  should  determine 
accurately  the  purpose  and  reason  of  each  of  the  respec- 


IMPORTANCE  OF  SELF-STUDY  287 

tive  functions,  and  then,  not  forgetting  their  interde- 
pendence upon  one  another  and  that  all  should  work  in 
harmony,  should  endeavor  to  do  that  which  will  best 
facilitate  the  functional  activity  with  the  least  expenditure 
of  energy. 

There  are  a  number  of  ways  in  which  the  study  of  per- 
sonal hygiene  may  be  advantageously  pursued,  but  for 
practical  purposes  one  of  the  best  is  to  consider  it  with 
respect  to  the  main  groups  of  organs  and  functions  of  the 
body,  keeping  always  in  mind,  however,  the  correlation 
of  these,  and  that  no  part  of  the  body  can  be  entirely 
independent  of  the  rest.^  Nevertheless,  the  hygiene  of 
infancy  is  a  study  by  itself,  for  it  is  in  that  epoch  of  life 
that  the  plastic  constitution  can  be  and  is  molded  most 
readily  by  all  the  influences  of  the  environment,  whether 
for  good  or  evil,  and  it  is  at  that  time  that  salutary  efforts 
are  to  be  made  with  greatest  hope  of  success  and  eventual 
good. 

Moreover,  th'e  principles  of  personal  hygiene  may  be 
more  readily  taught  to,  and  inculcated  in,  the  young,  but 
with  much  greater  difficulty  can  we  affect  the  mature  or 
aged;  for  we  are  all  creatures  of  many  habits,  and  in  the 
mature  adult  the  impress  of  these  may  resist  to  the  utmost 
any  and  all  endeavors  to  modify  or  remove  them. 

Too  much  stress  cannot  be  laid  upon  the  fact  that  it  is 
the  constitution,  the  nature  of  the  inherent  tissue,  that 
controls  or  modifies  the  inception,  development,  and  pro- 
gress of  many  of  the  ills  of  life,  and  that  whether  this  in 
its  normal  and  highest  vigor  be  a  bequest  of  heredity  or 
be  attained  only  by  the  most  careful  attention  to  details 
in  the  practise  of  the  art  of  hygiene,  it  should  always  be 
looked  upon  as  the  most  valuable  physical  possession  of 
the  individual. 


>  This  method  has  been  followed  in  Pyle's  Manual  of  Personal  Hygiene, 
to  which  the  reader  is  referred  for  an  admirable  discussion  of  the  sub- 
ject, which  must  be  treated  all  too  briefly  here.  The  writer  would  also 
recommead  Starr's  Hygiene  of  the  Nursery  to  all  who  desire  specific 
and  authoritative  information  concerning  the  young. 


288  PERSONAL  HYGIENE 

To  state  again  what  has  already  been  written:  "The 
essence  of  sanitation  is  to  secure  perfect  health,  to  increase 
the  inherent  power  to  resist  noxious  and  harmful  influ- 
ences, and  to  make  all  the  surroundings  and  environments 
of  the  body  pure  and  free  from  depressing  factors." 

With  this  preface,  the  following  discussions  are  added 
in  the  hope  that  they  may  be  of  assistance  in  determining 
the  way  of  right  living  and  in  securing  the  welfare  and 
health  of  each  individual. 


HEREDITY. 

In  the  broad  biologic  sense,  heredity  is  the  transmission  of 
a  series  of  characteristics  to  and  by  a  fused  cell,  formed  from 
two  cells  furnished  by  respective  parents,  which  carries 
on  its  evolution  under  certain  governing  impressions 
indelibly  stamped  by  the  two  parental  lines  of  descent; 
but,  in  the  ordinary  use  of  the  term,  it  may  be  defined  as 
the  transmission  to  the  offspring  from  parent  or  ancestor 
of  any  trait,  type,  temperament,  characteristic,  or  predis- 
position which  has  a  governing  or  influencing  effect  upon 
the  growth  or  nature  of  that  offspring.  These  transmitted 
impressions  may  be  either  for  good  or  for  evil. 

"  It  shows  an  incorrect  conception  of  the  law  of  heredity 
to  look  for  a  return  of  identical  phenomena  in  each  new 
generation."^  Also,  "we  do  not  mean  exclusively  by 
heredity  the  very  complaint  of  the  parent  transmitted 
to  the  children,  with  the  identical  symptoms,  both  physi- 
cal and  moral,  observed  in  the  progenitors.  By  the  term 
heredity  we  understand  the  transmission  of  organic  dis- 
positions from  parents  to  children. "^  In  true  hereditary 
disease  the  faulty  conditions  must  be  transmitted  in  the 
germ-plasm,  and  not  be  due  simply  to  accidental  factors 
affecting  the  embryo  during  its  fetal  development,  the 
results  of  the  latter  being  congeniial  rather  than  inherited. 


1  Moreau,  Psychologie  morbide, 

2  Morel,  Traite  des  D6g6n6rescence8. 


MARRIAGE  289 

Consequently,  as  hygienists,  we  must  use  the  influence 
and  power  that  we  have  to  further  the  transmission  of 
only  beneficial  or  elevating  characteristics,  and  to  prevent 
the  bequest  of  harmful  influences  and  hereditary  diseases 
to  the  generations  to  come.  "The  germ  of  the  unborn 
infant  must  be  complete  and  untainted  in  all  its  nature, 
otherwise  we  cannot  hope  for  a  vigorous  and  perfect 
growth  or  development." 

As  the  family  is  the  foundation  of  the  State,  and  society 
is  a  congregation  of  men  for  the  purpose  of  acquiring 
greater  power  and  more  comforts  through  mutual  co- 
operation, the  latter,  whether  domestic  or  civil,  has  some 
right  to  make  men  understand  that  they  must  care  for  the 
health  of  the  generations  to  follow,  and  to  enact  reasonable 
laws  looking  to  the  prevention  or  obliteration  of  transmis- 
sible infirmities.  And  history  seems  to  show  that  no  great 
nation  has  ever  been  destroyed  or  overwhelmed  until  its 
people  had  first  neglected  or  abused  the  laws  of  hygiene, 
heredity,  and  sociology. 

MARRIAGE. 

We  find  that  a  married  couple  have  generally,  beside 
themselves,  the  welfare  of  from  three  to  five  human  beings 
within  their  keeping.  To  produce  healthy  children  and 
ones  not  prone  to  disease,  both  parents  should  possess 
good  constitutions,  and  they  should  take  great  care  not  to 
weaken  these  by  excesses  of  any  kind,  physical  or  mental, 
nor,  as  far  as  lies  in  their  power,  by  any  chronic  disease. 
It  is  evident  that  children  of  parents  that  have  been  con- 
scientious observers  and  followers  of  Nature's  laws  must 
have  a  better  chance  for  health  and  superiority  all  their  lives. 

In  this  climate  the  proper  age  for  marriage  is  consid- 
ered to  be  about  twenty-four  or  twenty-five  for  the  man, 
,  and  nineteen  or  twenty  for  the  woman,  though  this  must 
vary  with  the  state  of  development  of  the  parties  con- 
cerned. Some  of  both  sexes  mature  at  a  considerably 
earlier  period  than  do  others,  and  it  would  be  unjust  to 
19 


290  PERSONAL  HYGIENE 

say  that  they  were  not  fit  for  the  duties  of  marriage  till 
they  reached  the  age  of  the  maturing  of  slower-growing 
ones.  Usually,  however,  before  the  ages  given,  develop- 
ment is  not  complete  and  the  whole  organism  is  in  a 
transition  state.  We  know  that  the  use  of  any  organ 
before  it  has  attained  its  complete  growth  or  development 
is  very  apt  to  cause  exhaustion  or,  perhaps,  premature 
degeneration  of  that  organ,  and  we  cannot  but  believe 
that  children  developed  in  immature  sexual  organs  must 
be  deficient  in  vital  force  and  energy.  It  is  often  notice- 
able that  a  child  apparently  strong  and  vigorous  may 
have  but  little  power  to  resist  disease  or  may  even  be 
strongly  predisposed  to  some  infirmity;  in  such  cases 
there  will  likely  be  some  defect  or  taint  in  the  parent 
stock. 

Distinguishing  characteristics  are  more  likely  to  be 
transmitted  in  the  early  married  life  of  parents,  because 
their  organs  and  forces  are  then  more  vigorous;  but  if  a 
couple  marry  when  quite  young  and  before  their  own 
organs  are  fully  developed,  their  elder  children  may  be 
more  deficient,  mentally  and  physically,  than  their  later 
ones. 

Late  marriages  are  not  likely  to  be  so  fruitful  as  earlier 
ones,  possibly  owing  to  the  increased  difficulty  of  parturi- 
tion on  the  part  of  the  mother  and  her  consequent  unwill- 
ingness to  undergo  the  ordeal  more  than  a  few  times. 
But  healthy  middle-aged  persons,  who  have  married  late, 
may  have  even  healthier  children  than  those  who  have 
married  too  early. 

In  features,  constitution,  sense-organs,  shape  of  head, 
etc.,  the  child  is  most  apt  to  resemble  the  father;  while 
it  will  likely  follow  the  mother  in  the  shape  of  the  trunk 
and  in  the  formation  of  internal  organs.  The  character 
and  mental  qualities  of  the  child  may  come  from  either 
parent  or  from  both.  Maternal  impressions,  habits,  or 
conditions  during  pregnancy,  especially  if  continuous  or 
persistent,  undoubtedly  often  have  a  marked  effect  upon 
the  coming  infant.     So  also  do  maternal  toxemias  or 


INHERITED  AND  CONGENITAL  DISEASES     291 

other  depraved  conditions  of  the  mother's  system,  though 
occasionally  such  influences  apparently  do  not  do  as  much 
harm  as  we  would  anticipate.  There  may,  however,  even 
be  actual  and  direct  infection  of  the  child  through  the 
placenta.  In  fact,  "  intra-uterine  infections  and  modifica- 
tions of  the  fetus  are  more  frequent  and  more  important 
than  conditions  of  true  inheritance  of  disease."^ 

INHERITED    AND   CONGENITAL   DISEASES. 

Hereditary  influences  are  generally  transmitted  directly 
from  parent  to  child,  but  w^e  occasionally  find  a  cessation 
of  a  trait  or  predisposition  for  one  or  more  generations 
and  then  a  recurrence.  To  such  a  peculiarity  we  give  the 
term  atavism.  "A  family  history  of  less  than  four  genera- 
tions has  only  a  limited  value." 

An  hereditary  malady  may  be  actually  existent  at  birth 
and  be  transmitted  directly  from  parent  to  offspring — 
as  syphilis,  structural  deformity,  mental  or  nervous  defect, 
etc.;  or  there  may  only  be  an  inherited  predisposition  to 
the  disease,  as  toward  tuberculosis,  etc.  Physicians  have 
thus  a  twofold  duty:  first,  to  do  all  they  can  to  guard 
against  the  transmission  of  such  diseases;  second,  to 
combat  the  disease  or  any  tendency  to  it  as  soon  as  the 
first  symptoms  thereof  are  discovered  or  it  is  suspected  in 
the  child.  The  first  duty  can  be  accomplished,  theoret- 
ically, by  preventing  generation  and  production  on  the 
part  of  those,  unfit  to  produce  healthy  offspring,  and 
practically,  within  certain  limits,  by  fighting  the  causes 
and  their  effects  in  the  parent  individual,  especially  at 
the  ages  or  times  when  these  have  the  greatest  force  or 
are  most  apt  to  manifest  themselves.  For  the  second,  the 
child  must  be  immediately  placed  in  the  most  favorable 
hygienic  surroundings,  and  everything  possible  done  to 
prevent  the  further  development  of  the  disease  or  predis- 
position.    In   many   cases  such   early   interference  will 

1  McFarland. 


292  PERSONAL  HYGIENE 

accomplish  much  good,  and  the  disease  may  be  averted 
entirely.  Especially  is  this  true  of  those  inheriting  the 
tuberculous  diathesis. 

Too  often  the  child  of  a  tuberculous  parent  is  exposed 
after  birth  to  the  same  conditions  that  served  to  develop 
the  disease  in  the  parent,  and  its  inherited  predisposition 
to  the  malady  is  intensified  by  the  environment  of  a  damp 
and  undrained  soil,  a  dark  and  un ventilated  house,  etc., 
and  by  insufficient  or  improper  food,  until  infection  is 
all  too  easily  acquired,  and  the  child  that  might  have 


f 


6^m  niDi^ooii 

Fig.  79. — Eighteen  feeble-minded  children  and  grandchildren.  A 
feeble-minded  woman  married  an  alcoholic  man.  Seven  of  their  chil- 
dren were  feeble-minded,  two  were  alcoholic  and  one  boy  died  in  infancy. 
Two  of  the  children  (both  feeble-minded)  have  children.  All  eleven 
were  feeble-minded.     Squares  are  males,  circles  are  females.^ 

been  saved  becomes  an  early  victim  of  the  ignorance, 
carelessness  or  neglect  of  those  who  should  have  fostered 
it  with  extremest  care  and  solicitude.  On  the  other  hand, 
the  apparently  complete  eradication  of  the  transmitted 
predisposition  from  many  children  whose  inheritance  has 
been  as  bad,  but  who  were  promptly  removed  from  the 
unsanitary  environment  of  their  birth,  shows  how  much 
this  one  influence  may  work  for  good. 

The  most  important  of  the  supposedly  hereditary  or 
transmissible  affections  are  syphilis,  tuberculosis,  scrofula, 


^  Figs.  79  and  80  are  from  a  Bulletin  on  The  Transmission  of  Feeble- 
mind,  issued  by  the  Department  of  Public  Health  and  Charities  of 
Philadelphia,  1910. 


INHERITED  AND  CONGENITAL  DISEASES     293 

cancer,  gout,  hysteria,  epilepsy,  certain  physical  deform- 
ities, certain  skin  diseases,  insanity,  feeble-mindedness, 
and  criminal  tendencies  of  various  kinds.  But  do  not 
forget  that  what  may  appear  to  be  a  direct  and  actual 
inheritance  of  a  disease  may  only  be  the  production  of  the 
disease  in  that  person  by  the  same  agents,  environments, 
and  morbid  conditions  as  caused  or  favored  the  disease 
in  the  parent.  However,  even  here  there  is  very  possibly 
a  transmitted  predisposition  to  the  acquirement  of  the 


0  00  0  0 


4  .n%.  i  B  B  Q  m  B  B  B  B 

Fig.  80. — Second  generation  apparently  normal  (six  feeble-minded 
appear  in  the  third  generation).  A  feeble-minded  woman,  possessing  a 
tuberculous  brother,  married  an  alcoholic  man.  Result,  three  (appar- 
ently) normal  girls,  one  normal  boy  and  one  alcoholic  son.  One  of  the 
girls  married  an  alcoholic  man.  Three  feeble-minded  sons,  two  normal 
sons  (twins),  two  miscarriages  and  a  child  dying  in  infancy  resulted.  The 
other  two,  apparently  normal  girls,  each  produced  feeble-minded  ofT- 
spring;  one  a  boy,  the  other,  two  boys.  Squares  are  males,  circles  are 
females.  Small  black  circle  indicates  miscarriage.  This  chart  also 
illustrates  atavism  in  its  relation  to  feeble-mindedness. 


disease,  rendering  it  all  the  more  easy  for  it  to  develop 
and  to  manifest  its  symptoms  upon  slight  provocation. 
Therefore  there  should  be  no  marriage  between  persons 
inheriting  predispositions  to  the  same  disease,  especially 
if  they  be  relatives,  and  "a  person  affected  with  heredi- 
tary or  well-marked  constitutional  syphilis,  or  having  a 
strong  consumptive  taint,  or  tendency  to  mental  unsound- 
ness (or  weakness)  should  not  marry  at  all." 
Defective  eyesight  is  very  apt  to  be  transmitted  to 


294  PERSONAL  HYGIENE 

children,  and  the  latter  should  be  carefully  examined 
and,  if  necessary,  fitted  with  proper  glasses  beiFore  being 
placed  at  school  or  at  any  work  requiring  much  use  of 
the  eyes. 

Infirmities  which  do  not  prevent  marriage  from  being 
fully  accomplished,  or  which  do  not  tend  to  the  degenera- 
tion of  the  offspring,  are  not  good  reasons  alone  for  for- 
bidding marriage,  but  all  that  have  such  a  tendency  are. 
A  man  should  not  marry  a  woman  too  far  advanced  in 
life,  nor  one  that  is  very  feeble,  delicate,  or  deformed, 
especially  as  to  the  chest  or  pelvis.  Hysteria,  convul- 
sions, and  epilepsy  due  to  organic  disease  should  prevent 
a  woman  from  marrying,  though  some  extremely  nervous 
and  hysterical  women  are  much  benefited  by  marriage 
and  have  healthy  children.  So  with  many  women 
who  have  uterine  congestions  and  displacements  before 
marriage. 

Evidence  seems  to  indicate  that  marriage  between  rela- 
tives is  reprehensible,  and  that  the  danger  increases  with 
the  nearness  of  the  relationship,  since  the  children  of  such 
marriages  are  prone  to  disease  and  to  defects  in  the  sense- 
organs,  especially  the  eye  and  ear,  or  in  mental  qualities. 
But  upon  closer  investigation  it  is  probably  more  nearly 
true  that  "the  objection  to  consanguineous  marriages  lies 
not  in  the  bare  fact  of  the  relationship  (of  the  parties  con- 
cerned), but  in  the  fear  of  their  having  similar  vitiations 
of  constitution."  Few  families  or  persons  are  absolutely 
healthy  or  free  from  taint,  and  "it  may  safely  be  asserted 
that  when  both  parents  are  possessed  of  a  physiological  or 
pathological  congenital  characteristic,  that  characteristic  is 
almost  certain  to  be  repeated  in  an  aggravated  form  in  the 
offspring."^  We  can,  accordingly,  easily  understand  that 
"in  consanguineous  marriages  the  real  danger  is  in  the 
strong  probability  that  both  parents  have  some  distinct 
taint  of  degeneration,  which  is  liable  to  be  increased  in 
their  children,  but  which  might  possibly  disappear  if  each 

1  Lawrence  Irwell,  Philadelphia  Medical  Journal,  July  21,  1900. 


EXERCISE  295 

married  a  person  not  bearing  the  same  or  some  closely 
allied  character.  The  marriage  of  two  individuals  of  the 
phthisical  type,  whose  families  were  strangers  to  each 
other,  would  be  as  productive  of  evil  as  the  marriage  of 
first  cousins  who  were  phthisically  inclined."^  However, 
any  advice  on  the  subject  must  depend  upon  the  special 
circumstances  in  each  case,  but  chiefly  on  the  health  and 
degree  of  relationship  between  the  parties. 

EXERCISE. 

Exercise  is  generally  considered  to  mean  simply  the 
action  of  the  voluntary  muscles,  but  it  has  a  wider  mean- 
ing than  this.  Every  organ  in  the  body  is  capable  of 
being  exercised  in  some  way  or  other;  and  if  not  properly 
exercised,  an  abnormal  stdte  is  almost  certain  to  ensue. 
"Life  is  organization  in  action."  Each  organ  has  its 
own  special  st'mulus,  and  if  this  be  normal  in  amount 
and  character,  we  should  have  health.  Also,  the  trained 
use  of  an  organ  makes  it  more  effective  in  the  performance 
of  its  functions.  But  deficiency  in  exercise  favors  a  lack 
of  nutrition,  wasting  in  size,  and  eventually  degeneration 
of  tissue;  while,  on  the  other  hand,  too  much  work  may 
favor  hypertrophy  and  tissue  degeneration. 

Proper  muscular  exercise  is  highly  beneficial  to  health, 
and  in  the  end  actually  necessary  to  the  proper  perform- 
ance of  functions  in  other  organs;  it  is  consistent  with 
and  necessary  to  health.  But,  to  be  of  value,  the  exercise 
must  not  only  be  regular,  but  must  also  consist  of  move- 
ments of  sufficient  force  to  necessitate  energetic  contrac- 
tion of  the  muscles;  we  must  do  work.  This  necessitates 
resistance  as  an  element,  and  we  may  define  physical 
exercise  as  voluntary  labor.  We  need  the  resistance  to 
obtain  the  proper  contraction  of  the  muscles,  the  contrac- 
tion for  their  disintegration,  the  disintegration  for  their 
renewal,    etc.;   for   we   know    that   upon    the    constant 

'  Lawrence  Iswell.  Philadelphia  Medical  Journal,  July  28,  1900. 


296  PERSONAL  HYGIENE 

destruction  and  disintegration  of  tissues  depends  their 
subsequent  renovation,  and  that  the  strength  and  vigor  of 
all  parts  of  the  body  and  of  the  whole  body  depend  upon 
its  newness. 

Beside  the  fact  that  proper  physical  exercise  makes  the 
voluntary  muscles  larger,  harder,  stronger,  and  more 
quickly  responsive  to  the  will,  and  that  it  increases  the 
functional  capacity  of  the  involuntary  muscles  employed, 
it  largely  promotes  health  and  strength  by  quickening  the 
circulation  and  increasing  the  respiratory  powers.  Dur- 
ing muscular  action  (contraction)  there  is  a  conversion  of 
potential  energy  into  motion,  a  call  for  more  food,  an 
increased  demand  for  and  consumption  of  oxygen,  and  an 
increased  production  of  and  elimination  of  carbon  dioxide 
and  other  waste  matters. 

This  increased  demand  for  oxygen  and  elimination  of 
carbon  dioxide  necessitate  increased  action  of  the  respira- 
tory organs — the  lungs,  and  this  is  one  of  the  greatest 
advantages  of  physical  exercise.  The  respirations  are 
increased  in  frequency  and  depth,  the  lungs  expanded,  the 
air  vessels  flushed  out  and  refilled  with  each  inspiration. 
Doubtless  many  cases  of  pulmonary  tuberculosis  could  be 
prevented  or  cured  if  only  people  could  be  taught  to  take 
sufficient  and  suitable  exercise  and  to  breathe  properly,  for 
we  rarely  find  the  lungs  fully  expanded  except  in  the  out- 
door worker  or  athlete.  Consequently,  the  movements  of 
any  given  exercise  should  be  with  speed  and  force  sufficient 
to  quicken  and  deepen  the  respiration;  and,  conversely, 
if  any  severe  exercise  is  to  be  undertaken  or  a  course  of 
training  begun,  special  care  must  be  had  to  develop  the 
lung  capacity.^ 

A  man  exercising,  even  moderately  in  any  manner, 
inspires  considerably  more  air  than  when  reclining  at  rest, 

^  The  caution,  however,  should  be  given  here  that  persons  with  incip- 
ient tuberculosis,  or  with  a  marked  tendency  thereto,  should  not  take 
up  exercises  involving  deep  and  rapid  breathing,  except  under  the 
advice  of  a  competent  physician,  as  much  harm  may  result  in  some  cases 
from  such  unwonted  excitement  of  the  pulmonary  tissue. 


EXERCISE  297 

which  latter  amount  is,  for  an  adult,  about  480  cubic 
inches  per  minute.  Or,  as  Pettenkofer  has  shown,  a  man 
on  a  day  of  rest  absorbs  25  ounces  of  oxygen  and  throws 
off  32  ounces  of  carbon  dioxide  and  29  ounces  of  water;  on 
a  day  of  work  he  absorbs  33.6  ounces  of  oxygen  and  throws 
off  45  ounces  of  carbon  dioxide  and  72  ounces  of  water. 
In  other  words,  the  elimination  of  carbon  on  a  work-day 
is  more  than  three-fourths  of  a  pound. 

Muscular  exercise  is  necessary,  therefore,  for  the  proper 
elimination  of  waste  carbon  from  the  body,  and,  as  the 
action  of  the  muscles  is  checked  and  lessened  if  the 
carbon  dioxide  produced  by  their  action  is  not  immediately 
carried  off  by  the  blood  and  eliminated  by  the  lungs,  it 
follows  that  during  exercise  there  should  be  nothing  to 
impede  the  circulation  or  the  action  of  the  chest  and 
lungs,  and  that  all  tightness  of  clothing,  especially  about 
the  waist,  neck,  and  chest,  should  be  avoided.  Moreover, 
inasmuch  as  the  amount  of  carbon  dioxide  and  other 
waste  matters  eliminated  is  so  very  much  increased  during 
exercise,  a  much  larger  amount  of  pure  air  is  needed,  and 
all  rooms  and  buildings  wherein  exercise  is  to  be  taken 
should  be  well  ventilated. 

After  exercise  an  increased  amount  of  carbonaceous 
food  and  of  water  must  be  supplied  to  replenish  the  sys- 
tem for  what  has  been  eliminated.  The  increase  of  carbon 
food  is  probably  best  given  in  the  form  of  fat  rather  than 
of  the  carbohydrates,  though  there  is  some  difference  of 
opinion  on  this  point;  and  of  all  fluids,  water  is  doubt- 
less the  best  in  ordinary  cases  for  training.  As  a  general 
rule,  alcohol  is  harmful,  because  it  benumbs  and  deadens 
the  nerves  and  will,  and  because,  as  every  voluntary 
impulse  must  originate  in  the  brain,  anything  that  inter- 
feres with  the  communication  between  it  and  the  muscles 
must  lessen  the  promptness  with  which  they  respond 
and  the  consequent  efficacy  of  their  work.  The  advanced 
opinion  of  today  seems  to  discountenance  the  use  of 
alcohol  in  any  form  or  at  any  time  by  those  in  training 
for  contests  of  skill,  endurance  and  strength. 


298  PERSONAL  HYGIENE 

By  exercise  the  action  of  the  heart  is  increased  in  force 
and  frequency,  the  pulse  is  made  full  and  strong,  if  the 
work  be  not  too  excessive  or  sudden,  and  the  flow  of 
blood  and  other  fluids  is  increased  throughout  the  whole 
body.  As  long  as  the  heart  is  not  overtaxed  the  pulse- 
beats  are  regular  and  even,  though  suddenly  increased 
exertion  may  make  the  rate  very  rapid.  Ordinarily  exer- 
cise increases  the  rate  from  ten  to  thirty  beats  per  minute. 
Excessive  exercise  leads  to  palpitation  and  hypertrophy 
of  the  heart  (one  reason  why  any  extensive  training 
should  be  under  a  competent  trainer);  but,  on  the  other 
hand,  deficient  exercise  leads  to  a  weakening  of  the  heart 
muscle  and  heart  action,  and  probably  to  dilatation  and 
fatty  degeneration.  If  at  the  beginning  of  a  new  exercise 
the  heart  action  becomes  irregular,  rest  should  be  taken, 
and  the  exercise  then  begun  in  a  more  moderate  and 
gradual  way.  The  heart  stimulus  is  largely  due  to  the 
increased  amount  of  blood  in  its  cavities,  but  it  should  be 
remembered  that  the  venous  circulation  is  chiefly  due  to 
the  muscles.  "Every  muscle  is  a  little  heart,"  and  these, 
by  their  contraction,  constantly  tend  to  drive  the  blood 
onward  to  the  true  heart  and  lungs. 

Exercise  greatly  increases  the  amount  of  perspiration 
from  the  skin,  this  perspiration  containing  water,  salt, 
and  considerable  waste  matter.  The  evaporation  of  the 
water  tends  to  keep  the  body  cool,  but  on  account  of  the 
great  heat-production  there  is  not  much  danger  of  chilling 
the  body  during  exercise.  As  soon  as  work  is  stopped 
heat-production  is  checked,  the  body  cools  off  rapidly, 
especially  in  a  strong  draught  or  a  current  of  air, 
and  then  there  is  danger  of  chilling  unless  more  clothing 
be  added.  Flannel  is  best  for  this  purpose  because  it  is  a 
non-conductor  of  heat  and  hygroscopic  and  so  prevents 
too  rapid  cooling  of  the  body.  Keep  the  skin  clean  so 
that  the  sweat-glands  may  be  unobstructed  in  the  per- 
formance of  their  functions. 

Exercise  increases  the  appetite,  partly  because  of  the 
increased  demand  of  the  muscles  for  food,  and  partly  on 


EXERCISE  299 

account  of  the  increased  circulation  of  the  blood  through 
the  vessels  of  the  alimentary  tract,  digestive  glands  and 
the  liver,  this  causing  a  more  perfect  digestion  of  food. 

If  exercise  be  taken  too  soon  before  meals,  either  the 
stomach,  by  calling  the  blood  from  the  exhausted  muscles, 
will  prevent  their  proper  repair  and  rest;  or  the  muscles, 
calling  the  blood  from  the  stomach,  will  prevent  the 
proper  formation  of  the  gastric  juice  when  food  is  intro- 
duced. If  exercise  be  taken  too  soon  after  eating,  it  is 
apt  to  prevent  the  flow  of  blood  to  the  organs  of  digestion 
and  the  formation  of  the  digestive  juices;  or,  by  forcing 
the  contents  of  the  stomach  into  the  intestines  before 
gastric  digestion  is  completed  and  before  the  food  has 
reached  a  condition  in  which  the  intestines  can  make  use 
of  it,  to  cause  intestinal  irritation  and  indigestion. 

Proper  physical  exercise  favors  a  symmetrical  brain 
development,  for  it  not  only  sends  more  blood  containing 
food  and  oxygen  to  this  organ,  but  exercise  of  the  func- 
tions of  the  centres  governing  the  action  of  the  muscles 
must  also  favor  the  growth  and  development  of  those 
centres.  "Hand  culture,  apart  from  its  value  per  se,  is 
a  means  toward  more  perfect  brain  culture,"  and  exer- 
cise by  itself  alone  is  truly  educational,  although  this 
feature  of  it  may  be  more  fully  developed  and  empha- 
sized by  proper  systems  and  methods.  The  great  trouble 
is  that  it  is  extremely  liable  to  be  misapplied,  misunder- 
stood, or  neglected. 

The  aim  of  training  should  be  to  increase  the  capacity 
of  the  lungs  and  the  breathing  power,  to  strengthen  the 
heart  and  the  circulation,  to  invigorate  the  brain  and 
nerve-centres,  to  improve  digestion  and  nutrition,  to 
make  the  muscles  more  powerful,  more  responsive  to  the 
will  and  their  capacity  for  endurance  greater,  and  to 
lessen  the  amount  of  adipose  tissue.  Systematic  exercise 
also  helps  one  to  resist  disease,  because  by  it  waste  mat- 
ters are  carried  off;  pores,  glands,  and  organs  are  kept  at 
work  and  healthy,  and  active  tissues  take  the  place  of 
weak  and  sluggish  ones. 


300  PERSONAL  HYGIENE 

Fatigue  is  due  to  lack  of  contractile  material  in  the 
muscles  to  continue  work,  to  the  exhaustion  of  nerve-force 
and  motor  impulses  from  the  brain,  and  to  accumulation 
of  waste  products,  possibly  leucomains,  in  the  muscle. 

Active  exercise  is  that  brought  about  by  one's  own 
movements;  passive,  that  produced  by  something  outside 
or  collateral  to  one's  own  power. 

It  is  hard  to  determine  how  much  exercise  any  given 
person  ought  to  take,  as  the  personal  equation  varies  so 
much.  The  average  healthy  man  should  probably  do 
work  equivalent  to  150  foot-tons  daily.  The  work  of 
walking  on  a  level  at  the  rate  of  three  miles  per  hour  is 
said  to  be  equal  to  that  of  raising  one-twentieth  of  the 
body-weight  through  the  distance  walked.  According  to 
this,  a  man  of  150  pounds  in  walking  one  mile  does  work 
equal  to  17.67  foot-tons,  and  his  total  daily  physical  labor 
should  be  equivalent  to  walking  about  nine  miles  at  the 
above  rate  to  get  the  proper  amount  of  daily  exercise. 
This  seems  like  an  excessive  amount,  but  if  the  actual 
physical  work  of  one's  customary  vocation  be  taken 
from  this,  it  will  probably  not  leave  so  very  much  for  the 
daily  health-task.  The  natural  disinclination  of  many 
to  exercise  grows  stronger  by  indulgence,  and  while 
urgent  reminders  are  wanting  and  the  evils  arising  from 
the  neglect,  abuse,  or  misuse  of  exercise  are  not  so  very 
immediate  or  apparent,  the  latter  are  still  certain  to  result, 
and  are  not  at  all  consistent  with  good  and  perfect  health. 

BATHING. 

In  health  we  make  use  of  baths  and  bathing  for  the 
cleansing  of  the  body,  the  stimulating  of  the  functions  of 
the  skin,  and  as  a  tonic  to  the  whole  system.  A  suitable 
bath  properly  taken  is  exhilarating  and  thoroughly  enjoy- 
able. Baths  are  also  to  be  employed  in  sickness  as  a 
means  of  cure,  but  such  use  of  them  is  foreign  to  the 
present  discussion. 

H.  C.  Wood  says:  "Cleanliness  and  the  maintenance 


BATHING  301 

of  the  proper  condition  of  the  skin  require  the  use  of  the 
bath  at  least  twice  a  week.  In  some  very  deHcate  persons 
the  general  bath  produces  marked  depression,  but  this  can 
almost  always  be  avoided  by  the  use  of  very  hot  water. 
If  the  hot  or  warm  bath  be  employed  habitually,  it  should 
be  preferably  taken  at  night,  and,  unless  under  very 
exceptional  circumstances,  the  hot  bath  should  always  be 
followed  by  cold  sponging  or  the  cold  shower-bath,  or  by 
a  plunge  into  cold  water."  The  temperature  of  a  cold 
bath  may  be  from  40°  to  75°  F.;  a  tepid  bath,  75°  to 
85°  F.-  a  warm  one,  85°  to  100°  F  ;  a  hot  one,  from 
100°  to  110°  F.  A  cold  bath  is  taken  not  so  much  for 
its  cleansing  as  for  its  tonic  and  stimulating  effects;  the 
others  are  used  mainly  for  their  cleansing  properties, 
though  if  followed  by  the  cold  sponge,  shower,  or  dip,  the 
sense  of  exhilaration  produced  will  be  marked. 

Cold  baths  taken  immediately  after  physical  exercise 
while  the  body  is  still  w^arm,  but  after  perspiration  has 
ceased,  and  followed  by  a  good  rubbing  and  friction  of 
the  skin,  dispel  fatigue  and  give  a  sense  of  buoyancy  and 
lightness.  The  shock  of  the  first  contact  of  the  water 
with  the  skin  is  but  momentary,  and  can  be  withstood 
by  most  persons  unless  there  be  serious  organic  disease; 
and  the  reaction  produced  certainly  compensates  for  the 
primary  discomfort.  If  the  bath  be  taken  in  the  open 
air^  there  is  the  additional  benefit  of  a  plentiful  supply 
of  fresh  air  for  the  lungs,  of  the  physical  exercise  and  the 
increased  circulation  induced  by  swimming  or  combating 
the  surf,  and,  if  in  the  sea,  of  the  stimulation  of  the  skin 
by  the  salt  water.  In  fact,  sea-bathing  may  be  advan- 
tageous to  a  marked  degree  where  the  circulation  and 
action  of  the  skin  are  sluggish. 

Those  who  are  subject  to  organic  heart  disease  should 
not  indulge  in  sea-bathing  nor  in  deep  fresh-water  bath- 
ing, since  a  sudden  tax  may  be  made  upon  the  strength 
and  the  heart  action  be  disturbed  or  checked.  Women 
who  are  menstruating  or  who  are  in  the  later  months  of 
pregnancy  should  not  take  cold  baths. 


302  PERSONAL  HYGIENE 

Baths  should  not  be  taken  too  soon  after  meals,  because 
digestion  may  be  lessened  or  entirely  stopped  by  the  blood 
being  called  from  the  stomach  to  the  skin  and  muscles, 
and  nausea  and  vomiting  thus  induced.  "There  can  be 
no  doubt  that  many  of  the  cases  that  are  called  'cramps,' 
and  which  frequently  result  in  drowning,  are  due  to  this 
cause."^  In  cold  baths  the  head  should  be  immersed 
first,  "to  avoid  increasing  the  blood-pressure  in  the  brain 
too  greatly,  which  might  result  if  the  body  were  gradually 
immersed  from  the  feet  upward."^ 

The  following  rules,  issued  by  the  English  Royal 
Humane  Society,  are  worth  noting:  "Avoid  bathing 
within  two  hours  after  a  meal,  or  when  exhausted  by 
fatigue,  or  when  the  body  is  cooling  after  perspiration. 
Avoid  bathing  altogether  in  the  open  air,  if,  after  having 
been  a  short  time  in  the  water,  there  is  a  sense  of  chilli- 
ness, with  numbness  of  the  hands  and  feet;  but  bathe 
when  the  body  is  warm,  provided  no  time  is  lost  in  get- 
ting into  the  water.  Avoid  chilling  the  body  by  sitting 
or  standing  undressed  on  the  banks  or  in  boats  after 
having  been  in  the  water.  Avoid  remaining  too  long  in 
the  water,  but  leave  the  water  immediately  if  there  is  the 
slightest  feeling  of  chilliness.  The  vigorous  and  strong 
may  bathe  early  in  the  morning  on  an  empty  stomach; 
the  young  and  those  who  are  weak  had  better  bathe  two 
or  three  hours  after  breakfast.  Those  who  are  subject  to 
giddiness  or  fainting,  or  who  suffer  from  palpitation  or 
other  sense  of  discomfort  of  the  heart,  should  not  bathe 
(out-of-doors)  without  first  consulting  their  physician. "^ 

After  any  kind  of  a  bath  the  body  should  be  thor- 
oughly dried,  not  only  to  restore  and  accelerate  the  cir- 
culation of  the  skin  by  the  friction  and  to  prevent  cooling 
by  the  evaporation  of  the  water,  but  also  to  prevent 
chafing  and  eczematous  eruptions  where  the  skin  is 
subject  to  the  friction  of  clothing.     Warm  or  hot  baths 

1  Rohe's  Text-book  on  Hygiene. 

2  Ibid. 

3  See  also  Sea  Air  and  Sea  Bathing,  by  John  H,  Packard. 


BATHING  303 

should  not  be  taken  if  the  person  is  to  be  exposed  to  the 
cold  within  several  hours,  and  the  same  rule  applies  to 
Turkish,  Russian,  or  vapor  baths;  so  the  former  had  best 
be  taken  in  the  evening,  and  the  latter  should  not  be 
taken  away  from  home,  especially  in  cold  weather,  unless 
the  bather  rests  for  a  time  after  the  bath,  and  then  wraps 
up  well  before  going  into  the  open  air. 

In  all  warm  baths  in  health  the  principal  object  is  to 
secure  the  cleansing  effects,  and  to  be  effective  their  use 
must  be  systematic.  The  pores  of  the  skin  are  self- 
cleansing  only  to  a  certain  degree,  and  the  free  use  of 
warm  w^ater  is  most  beneficial  in  removing  dry  epithelium, 
sweat,  dirt,  and  grease.  If  the  pores  of  the  skin  are  ob- 
structed, there  are  not  only  irritation  and  eruptions  of  the 
skin  produced,  but  more  work  is  thrown  upon  the  kidneys, 
and  these,  if  unsound,  will  break  down  the  quicker. 
Soft  water  is  to  be  preferred  for  ordinary  bathing  and 
washing,  because  it  often  prevents  or  lessens  cutaneous 
irritation  and  because  it  saves  soap. 

Public  baths  have  become  a  marked  feature  in  the 
scheme  of  municipal  sanitation  of  a  number  of  cities,  and 
are  of  benefit  not  only  directly,  but  as  a  means  of  incul- 
cating a  habit  of  cleanliness  in  those  who  use  them. 
Where  possible,  separate  baths  should  be  provided  for  the 
two  sexes,  and  all  should  be  at  all  times  under  competent 
and  strict  supervision.  There  is  some  danger,  however,  of 
the  spread  of  infection,  especially  of  skin  diseases,  in  the 
use  of  swimming  pools,  or  of  individual  bath-tubs,  and 
shower  booths  should  always  be  provided  in  preference 
to  the  latter.  For  the  same  reason  the  water  in  swimming 
pools  should  be  frequently  changed,  and  it  is  also  well  to 
attempt  to  render  it  aseptic  by  the  addition  of  small 
quantities  of  certain  chemicals,  such  as  chlorinated  lime 
or  copper  sulphate. 

A  Turkish  bath  consists:  (1)  Of  a  dry,  hot-air  bath 
at  a  temperature  of  from  120°  to  170°  F.,  or  even  higher, 
for  from  ten  to  thirty  minutes,  which  causes  in  most  per- 
sons profuse  perspiration  with  no  sense  of  discomfort, 


304  PERSONAL  HYGIENE 

but  rather  a  pleasant  sensation.  After  this  come:  (2)  A 
hot  shower-bath  to  wash  off  the  sweat.  (3)  Shampooing, 
massage,  and  scrubbing  to  remove  thoroughly  all  dirt, 
loose  epithelium,  and  perspiration  from  the  skin.  These 
take  place  in  moist  air  at  from  100°  to  110°  F.  (4)  A 
warm  shower-bath  gradually  changing  to  a  cold  one,  and 
then  a  thorough  drying  of  the  body  and  a  rest  for  a  quarter- 
or  half-hour.  A  Russian  bath  differs  from  this  only  in 
that  moist  air  at  150°  F.  or  under  is  used  instead  of  dry 
air  for  the  first  bath. 

It  has  been  said  "that  a  person  ought  never  stay  in 
either  the  hot-air  or  steam-room  if  in  anywise  oppressed, 
or  to  use  very  cold  water  afterward  if  one  feels  any 
shrinking  from  it."  Nor  should  one  who  is  very  corpu- 
lent or  who  has  organic  heart  disease  take  a  Turkish  or 
Russian  bath  without  the  advice  of  a  physician.  But  for 
healthy  persons  they  are  quite  pleasant  and  in  most  cases 
beneficial,  provided  they  are  not  taken  too  often  and  that 
one  does  not  indulge  in  them  too  long  at  a  time. 

The  terms  sun-baths,  mud-baths,  sand-baths,  and  pine- 
needle  baths  are  self-explanatory.  These  are  used  in 
treating  certain  diseases,  and  are  supposed  to  be  espe- 
cially beneficial  in  rheumatic  affections. 

CLOTHING. 

There  is  scarcely  anything  that  can  be  said  on  this 
subject  with  which  almost  every  one  of  ordinary  intelli- 
gence is  not  in  some  respects  conversant.  According  to 
Poore,  the  main  objects  to  be  sought  in  clothing  the  body 
are :  "  ( 1 )  To  maintain  the  temperature  and,  by  preventing 
the  loss  of  animal  heat,  to  diminish  to  some  extent  the 
demands  for  food.  (2)  To  allow  the  chief  heat-regulating 
mechanism — i.  e.,  the  evaporation  from  the  skin — to  pro- 
ceed with  as  little  hindrance  as  possible.  (3)  To  allow  all 
muscular  acts  the  greatest  possible  freedom,  and  to  avoid 
the  compression  of  the  body  in  so  far  as  may  be  possible. 
(4)  To  protect  the  body  from  heat,  cold,  wind,  and  rain. 


CLOTHING  305 

(5)  To  disguise  as  little  as  may  be  the  natural  beauties 
of  the  human  figure."^ 

The  substances  from  which  articles  of  clothing  are 
usually  manufactured  are  wool,  silk,  cotton,  linen,  leather, 
and  furs,  although  almost  everything  that  can  possibly 
be  fashioned  to  suit  the  needs  or  fancies  of  the  wearer  is 
or  has  been  utilized  for  the  purpose.  Goods  of  all  manner 
and  kind  are  woven  from  the  first  four  substances  men- 
tioned, either  singly  or  in  combination  one  with  another, 
and  felts  are  made  from  wool,  hair,  or  fur,  these  latter 
being  made,  not  by  weaving,  but  by  an  interlacing  and 
matting  together  of  the  fibres  by  pressure  and  rubbing. 

Wool. — In  a  general  sense  wool  is  probably  the  most 
valuable  of  clothing  materials,  since  in  a  variable  climate 
or  where  there  are  sudden  changes  of  temperature  it  is 
the  safest  for  the  wearer  to  use.  While,  taking  fibre  for 
fibre,  it  probably  does  not  vary  so  much  from  linen  or 
cotton  as  a  heat-conductor  as  is  generally  believed;  it  is 
usually  woven  in  such  a  way  as  to  entangle  large  quan- 
tities of  air  in  its  meshes,  thus  preventing  either  sudden 
lowering  or  raising  of  the  body-temperature,  since  dry  air 
is  an  especially  good  non-conductor  of  heat.  Moreover, 
wool  is  very  hygroscopic,  readily  taking  up  water  and 
perspiration  and  giving  them  off  slowly,  thus  reducing 
the  cooling  by  evaporation  to  a  minimum  and  regulating 
the  heat-dissipation  of  the  body.  All  who  are  subject 
to  rheumatism  or  to  such  disturbances  of  health  as  to 
render  them  susceptible  to  sudden  temperature-changes 
should  wear  woollen  garments  next  the  skin  the  year 
round,  varying  the  thickness  and  weight,  of  course,  to 
suit  the  season;  and  children  and  others  subject  to 
digestive  disturbances  will  usually  be  greatly  benefited 
by  the  constant  use  of  a  woollen  (or,  in  case  that  is  too 
heavy,  a  silken)  band  about  the  abdomen. 

As  it  is  ordinarily  woven,  some  persons  cannot  tolerate 
wool  next  the  skin  on  account  of  its  irritating  properties. 

» Stevenson  and  Murphy,  Treatise  on  Hygiene. 
20 


306  PERSONAL  HYGIENE 

These  latter  are  obviated,  however,  if  the  undergarments 
be  made  of  pure  wool  woven  by  methods  similar  to  that 
introduced  by  Jaeger,  or  of  a  mixture  of  wool  or  cotton, 
or  by  wearing  a  garment  of  linen  or  cotton  net  next  the 
skin  and  underneath  the  woollen  underclothing.  The 
Jaeger  method,  by  the  way,  is  said  to  provide  for  the 
escape  of  moisture  from  the  material  and  for  the  free  per- 
meation of  air  through  its  interstices. 

Silk. — Silk  is  an  excellent  non-conductor  of  heat,  and 
is  almost  as  hygroscopic  as  wool,  so  that  it  is  suitable 
material  from  which  to  make  warm  clothing.  Its  great 
natural  beauty  and  the  facility  with  which  it  takes  coloring 
matter  also  make  it  desirable  from  an  esthetic  stand-point, 
while  its  great  disadvantage  is  its  high  cost.  For  those 
who  cannot  wear  wool  next  the  skin  and  to  whom  cost 
is  no  objection,  silk  is  an  excellent  material  for  under- 
garments. 

Cotton. — Of  all  the  fibres,  cotton  is  probably  the  most 
generally  used  for  clothing.  It  is  not  so  hygroscopic  by 
far  as  wool,  but  it  is  hard  and  durable,  and  is,  above  all, 
cheap,  so  that  it  furnishes  the  bulk  of  the  clothing  for  the 
masses.  If  smoothly  woven  and  of  a  light  color,  it  makes 
extremely  cool  garments  for  warm  climates  or  seasons. 
On  the  other  hand,  if  warm  clothes  are  desired,  the 
cotton  must  be  woven  so  as  to  have  large  air-spaces  in 
the  fabric,  thus  making  it  resemble  the  ordinary  woollen 
clothing  in  texture  and  partly  in  function,  and  should 
be  of  a  dark  color.  Cotton  should  not  be  worn  next  the 
skin  by  those  subject  to  disturbance  by  sudden  tempera- 
ture-changes, nor  during  exercise,  unless  in  the  latter  case 
it  is  changed  immediately  after  the  exercise  or  additional 
clothing  is  added  to  the  body  to  prevent  too  rapid  evapor- 
ation and  cooling. 

Linen. — Linen  is  valued  for  its  purity  of  color  when 
bleached,  and  for  its  durability.  It  is  more  expensive 
than  cotton,  and  its  hygroscopic  and  heat-conducting 
properties  are  about  the  same  as  the  latter.  It  is  especially 
desirable  for  use  in  clothing  for  hot  climates  and  for 


CLOTHING  307 

articles  of  dress  that  are  easily  soiled  and  need  frequent 
cleansing. 

Furs. — Furs  provide  extreme  protection  against  the 
wind  and  cold,  both  on  account  of  the  impermeability 
of  the  skin  and  of  the  large  quantity  of  air  entangled  in 
the  fur  itself. 

Leather. — Leather  is  utilized  for  foot-coverings,  etc.,  on 
account  of  its  durability,  pliability,  and  practical  imper- 
viousness  to  moisture,  especially  when  oiled;  and  in  cold 
countries  is  also  used  for  body  garments  on  account  of  its 
resistance  to  the  wind  and  the  efficacy  with  which  it  keeps 
the  body  surrounded  wath  a  layer  of  warm  air. 

Rubber. — With  the  possible  exception  of  rubber,  which 
is  especially  useful  for  the  protection  which  it  gives  from 
wind  and  rain,  other  materials  from  which  clothing  is  made 
need  not  be  mentioned  here,  because  of  the  comparative 
rarity  of  their  use  and  their  close  resemblance  to  those 
already  named.  The  value  of  any  material  for  clothing 
purposes,  however,  may  be  said  to  depend  upon  the  slow- 
ness with  which  it  permits  the  passage  of  heat  to  or  from 
the  body  and  the  evaporation  of  water,  the  amount  of  air 
its  meshes  contain,  its  impermeability  to  the  wind,  or  else 
its  special  adaptability  to  some  particular  purpose. 

Certain  materials  are  manufactured  from  combinations 
or  mixtures  of  two  or  more  of  the  four  fibres  first  men- 
tioned, and  it  sometimes  becomes  necessary  to  distinguish 
these  one  from  another  and  to  determine  the  proportion 
of  each  in  the  goods.  This  is  done  by  microscopic 
examination,  each  fibre  having  its  own  peculiar  char- 
acteristics, and  by  chemical  reactions.  Some  of  these 
latter  are  as  follows:  Wool  and  silk  dissolve  in  hot  liquor 
potassae  or  sodse  of  a  specific  gravity  of  1050,  while  cotton 
and  linen  are  not  affected.  Wool  and  silk  are  stained 
yellow  by  strong  nitric  or  picric  acid;  cotton  and  linen 
are  not.  Sulphuric  acid  affects  wool  but  little,  slowly 
dissolves  silk,  and  changes  cotton  or  linen  into  a  gelati- 
nous substance  that  is  colored  blue  by  iodine.  Hot 
concentrated  zinc  chloride  dissolves  silk,  but  not  wool; 


308  PERSONAL  HYGIENE 

and  copper  dissolved  in  ammonia  rapidly  dissolves  silk 
and  cotton,  linen  more  slowly,  but  only  slightly  swells 
wool. 

Cloths  are  often  sophisticated  in  the  process  of  manu- 
facture, and  their  value  greatly  lessened  thereby.  Wool 
is  mixed  with  "shoddy,''  which  is  made  from  old  and 
used  woollen  rags  torn  asunder  and  then  respun  with  an 
addition  of  fresh  wool;  silk  is  heavily  weighted  with 
salts  of  tin,  iron,  or  with  other  substances;  and  cotton 
and  linen  are  stiffened  and  glossed  with  an  excessive 
amount  of  starch,  white  earth  or  the  like.  Shoddy  can 
be  determined  by  the  use  of  the  microscope;  the  weighting 
of  silk  by  chemical  reactions  and  solutions;  and  over- 
starching,  etc.,  of  cotton  and  linen  by  washing  and 
drying. 

It  will  not  be  advisable  here  to  go  fully  into  considera- 
tion of  the  influence  which  the  shape  and  style  of  the 
individual  garments  of  ordinary  use  have  upon  health, 
for  that  would  require  a  much  longer  discussion  than  the 
present  space  permits;  but  the  general  rule  may  be  laid 
down  that  each  article  of  clothing  should  be  adapted 
to  the  peculiar  needs  and  occupation  of  the  wearer,  and 
that  it  should  in  nowise  interfere  with  the  proper  develop- 
ment, use,  or  physiological  functions  of  any  part  of  the 
body. 

Trite  and  hackneyed  as  is  the  subject,  the  writer  feels 
that  he  would  be  wanting  in  the  performance  of  his  duty 
if  he  failed  to  condemn  the  habits  and  fashions  of  dress 
that  demand  undue  constriction  of  the  trunk  of  the  body. 
All  sanitarians  practically  agree  upon  the  importance 
of  "vital  capacity,"  as  measured  by  the  development 
and  extent  of  expansion  of  the  thorax,  in  determining 
the  constitution  and  health  of  the  individual.  But  not 
only  may  the  corset  harm  by  interfering  with  the  func- 
tions of  respiration  and  circulation,  but  it  may  also  deform 
and  induce  even  more  serious  troubles  by  its  displacement 
of  the  abdominal  and  especially  of  the  pelvic  organs,  and 
by  the  grave  interference  with  the  nutrition,  tone,  and 


CLOTHING  309 

functions  of  all  of  these.  It  is  a  fair  challenge  to  any 
woman  who  declares  that  she  does  not  dress  too  tightly, 
to  ask  her  to  measure  honestly  her  waist  circumference 
and  expansion  both  with  and  without  the  garment  in 
question,  and  to  make  her  decision  accordingly.  And  it 
is  certainly  false  doctrine  to  teach,  as  is  so  often  done  to 
young  girls,  that  it  is  really  necessary  that  the  normal 
human  body  should  have  artificial  support.  The  natural 
muscles  kept  in  proper  training,  tone,  and  action  are  all- 
sufficient  to  give  the  most  perfect  and  most  beautiful 
human  form. 

Another  matter  of  serious  moment  is  the  harmful  influ- 
ence of  ill-fitting  and  improper  shoes  upon  the  structure 
and  function  of  the  foot.  This  was  demonstrated,  so 
far  as  men  are  concerned,  by  the  unduly  large  number  of 
men  rejected  for  military  service  in  the  recent  war  because 
of  defective  feet,  as  well  as  by  the  remarkable  improve- 
ment and  benefit  experienced  by  many  others  after 
wearing  for  a  short  time  the  army  shoe  made  upon  the 
normal  last.  How  much  more  serious  is  the  effect  of  the 
abnormal  styles  and  high  heels  of  women's  shoes  can  be 
readily  demonstrated  and  should  be  appreciated  by 
thoughtful  students  of  hygiene. 

When  exposed  to  the  sun's  rays  or  to  other  sources  of 
radiant  and  incandescent  heat,  fabrics  absorb  heat  irre- 
spective of  the  constituent  materials,  but  in  the  following 
order  as  regards  color:  white,  light  yellow,  dark  yellow, 
light  green,  Turkey  red,  dark  green,  light  blue,  and  black, 
the  latter  color  absorbing  more  than,  and  light  blue  almost 
twice  as  much  as,  white,  the  material  in  each  case  being 
the  same.  In  the  shade  the  degree  of  absorption  depends 
more  on  the  material  than  on  the  color. 

Lastly,  it  should  be  remembered  that,  as  disease  germs 
are  readily  conveyed  from  place  to  place  and  from  one 
person  to  another  by  the  clothing,  and  especially  by  that 
which  is  hygroscopic  by  nature,  care  should  be  taken  to 
keep  the  garments  in  as  cleanly  and  aseptic  condition  as 
possible,   to   disinfect  them   whenever  they  have  been 


310  PERSONAL  HYGIENE 

exposed  to  infection,  and,  for  those  who  are  much  among 
the  sick  or  liable  to  infection,  the  use  of  smooth,  closely 
woven,  non-hygroscopic  outer  or  overgarments  that  can 
be  readily  cleansed,  such  as  those  made  of  cotton  or  linen, 
is  to  be  highly  recommended. 

LIGHT. 

The  important  influence  of  sunlight  in  the  development 
and  maintenance  of  a  healthful  condition  in  all  higher 
organisms,  both  animal  and  vegetable,  is  well  known  by 
everyone,  but  as  yet  there  is  a  lack  of  information  as  to 
the  exact  physiological  methods  and  processes  which  are 
due  to  this  great  force.  We  know  that,  for  the  plants, 
chlorophyll  is  the  intermediary  agent  which  largely 
assists  in  the  conversion  of  carbon  dioxide  and  the  storage 
of  carbon  in  various  compounds,  and  that  the  presence 
and  action  of  this  chlorophyll  are  largely  dependent  upon 
the  light-supply;  while  for  the  animal  kingdom,  and  espe- 
cially for  the  human  race,  it  is  evident  that  the  effect 
of  sunlight  is  manifested  more  or  less  directly  in  the 
blood  and  skin,  though  the  whole  body  quickly  shows  a 
marked  appreciation  of  its  presence  or  absence.  But 
when  this  has  been  said,  there  is  little  else  that  can  be 
added  as  a  matter  of  positive  information.  No  one  knows 
just  how  the  pallid  and  anemic  child  that  has  been 
reared  in  the  shade  and  dark  is  converted  into  the  tanned 
and  ruddy  picture  of  health  in  so  short  a  time,  but  the 
results  are  unquestionable. 

The  subject  demands  further  study,  and  it  may  not  be 
out  of  place  to  indicate  one  or  two  directions  in  which  the 
investigation  may,  perchance,  be  wisely  pursued. 

In  the  first  place,  there  has  doubtless  been  too  little 
appreciation  of  the  fact  that  sunlight  in  its  totality  has 
many  other  rays  of  force  than  those  which  manifest  them- 
selves alone  to  our  sense  of  sight.  The  existence  of  the 
ultra-violet  rays  and  the  fact  that  these  are  more  powerful 
actinically  than  those  of  the  ordinary  spectrum  have 
been  satisfactorily  demonstrated,  and  the  only  question 


LIGHT  311 

is  as  to  what  the  true  physiological  power  and  influence  of 
these  invisible  rays  may  be.  It  is  not  certain  at  present 
that  some  of  them,  at  least,  are  not  closely  related  to  the 
manifestation  of  force  discovered  by  Rontgen,  and  there 
is  good  reason  to  believe  that  the  penetrative  powers 
of  light  as  regards  the  human  body  are  not  fully  known 
or  appreciated.^  Nor  can  we  tell  how  much  of  that  power 
of  the  sun  whose  effects  we  feel  and  see  is  in  nature  on 
that  border-land  between  light  and  electricity  that  is  as 
yet  so  vague  and  unknown. 

Again,  the  destructive  effect  of  sunlight,  and  of  light 
from  minor  sources  as  well,  upon  the  germs  of  disease  and 
other  low  forms  of  life,  and  upon  their  toxic  products,  is 
now  a  matter  of  common  knowledge,  though  many  are 
not  aware  that  it  has  been  proved  that  this  germicidal 
action  of  light  is  directly  in  relation  to  its  actinic  power. 
Especially  has  it  been  shown  that  the  ultra-violet  rays 
quickly  destroy  the  vitality  of  micro-organisms  and  the 
toxins  produced  by  them.  Considering  this,  together 
with  the  statements  in  the  preceding  paragraph,  may 
we  not  surmise  that  hostile  organisms,  even  in  the  deeper 
tissues,  are  overcome  both  in  this  way  and  by  the  improved 
condition  of  the  blood  due  to  the  light,  and  that  this 
hypothesis  helps  to  explain  the  good  results  that  follow 
the  open-air  treatment  of  many  diseases  and  abnormal 
conditions?  The  tubercle  bacilli  are  especially  susceptible 
to  its  influence,  and  everyone  should  know  that  an  abun- 
dance of  sunlight  is  just  as  essential  to  the  tuberculous 
patient  as  are  plenty  of  good  food,  pure  air,  or  proper 
clothing. 

Bie,  Finsen  and  others  have  done  much  to  develop 
the  treatment  of  disease  by  light,  whether  from  the 
sun  or  artificial  sources,  and  good  results  are  frequently 

1  Some  experiments  by  the  author  and  by  numerous  others  seem 
clearly  to  indicate  that  some  of  the  radiant  energy  from  the  sun,  and  in 
lesser  degree  from  other  sources  of  light,  is  able  to  penetrate  substances 
hitherto  considered  opaque,  and  to  produce  phenomena  similar  to  those 
due  to  the  Rontgen  rays.  Consequently,  if  the  experiments  referred  to 
are  well  founded,  the  penetrative  ability  of  this  energy,  as  regards  the 
human  tissues,  would  seem  to  be  more  than  probable. 


312 


PERSONAL  HYGIENE 


obtained  from  such  treatment,  especially  in  the  case  of 
cutaneous  or  superficial  diseases.  And  although  more 
might  be  said  in  reference  to  the  possible  and  probable 
chemical  activity  of  the  light  in  and  upon  the  metabolic 
processes  of  the  animal  body,  as  there  is  still  the  un- 


FiG.  81. — Heliotherapy,  Sea  Breeze  Hospital,  Sea  Gate,  New  York, 
March  18,  1913.  Cured  case  of  tuberculosis  of  the  knee.  No  sinus. 
(Hinsdale's  Atmospheric  Air  in  Relation  to  Tuberculosis.) 


certainty  of  hypothesis  and  theory,  it  may  be  wiser 
simply  to  leave  the  foregoing  suggestions  as  food  for 
thought  and  incentives  to  further  research  and  investi- 
gation. 

The  importance  of  an  abundance  of  daylight  in  all 
rooms  where  much  work  is  to  be  done  should  not  be 


LIGHT 


313 


overlooked.  Not  only  is  it  necessary  for  the  conservation 
of  the  influences  just  mentioned,  and  as  a  destroyer  of 
pathogenic  organisms,  but  it  is  also  more  agreeable  and 
safer  for  the  eyesight  than  any  form  of  artificial  light 
yet  devised.  An  important  aid  to  the  illumination  of 
dark  interiors  has  been  the  introduction  of  panes  or 
plates  of  glass  with  a  series  of  ridges  or  prisms,  which 
refract  and  diffuse  throughout  a  room  light  which  would 
otherwise  illuminate  it  but  partially  or  not  at  all.    The 


-"  :«^ia-_i- 

^^^^^if-. 

-  — ^^t 

-z-^-.  w— 

_ 

Fig.  82. — Action  of  prismatic  glass  in  projecting  light.    (Harrington.) 


prisms  are  made  with  various  angles,  and  may  be  placed 
either  in  the  ordinary  window  sash  or  in  projecting 
canopies,  according  to  whether  the  direct  light  from  the 
sky  is  obstructed  or  not.     (Fig.  82.) 

The  relation  of  artificial  lighting  to  ventilation  has 
been  discussed.  In  addition  to  this  point,  the  quantity 
of  light  supplied  and  its  steadiness  have  an  important 
bearing  on  the  hygienic  value  of  any  artificial  source  of 
illumination  that  it  may  be  necessary  to  employ. 


CHAPTER  IX. 
SCHOOL  HYGIENE. 

It  was  remarked  in  the  chapter  on  Personal  Hygiene 
that  the  best  time  for  applying  the  laws  of  hygiene  is  in 
the  days  of  childhood  and  youth,  for  then  the  whole 
organism  is  plastic  and  yields  readily  to  both  external 
and  internal  impressions  and  forces. 

This  being  so,  the  great  influence  of  the  factors  common 
to  school-life  may  be  readily  conceived,  and  inasmuch  as 
the  average  child  will  be  subject  to  them  for  a  large  part 
of  from  eight  to  ten  or  more  years,  the  importance  of  a 
study  of  school  hygiene  will  not  be  denied.  It  concerns 
the  parent,  the  physician,  and  the  citizen,  and  its  inves- 
tigations must  consider  the  personal  hygiene  of  the  scholar, 
the  conditions  of  his  health,  his  habits,  the  amount  of 
work  done,  the  sanitary  environment  and  requirements 
of  the  school-room  and  building,  the  furniture,  the  venti- 
lation and  heating,  and  the  influence  of  all  these  upon 
the  individual's  state  and  development. 

Next  to  the  scholar  himself  and  his  parents,  these 
matters  are  of  special  interest  to  the  physician,  for,  in  addi- 
tion to  being  one  who  from  his  special  training  and  educa- 
tion is  often  called  to  act  upon  school  committees  and 
boards  of  education,  or  as  a  medical  inspector  of  schools, 
he  has  to  treat  many  disturbances  of  health  in  the  young 
which  have  their  origin  or  cause  in  the  harmful  or  insani- 
tary conditions  of  school-life. 

There  are  disorders  to  which  all  children  are  subject 
whether  in  school  or  out;  but  a  special  class  are  markedly 
influenced  by  school-life  or  work,  and  to  these  abnormal 
conditions  we  may  give  the  term  "School  Pathology." 
Of  some  of  these,  overwork  is  the  cause;  others  are  set 
up  by  other  factors. 
(314) 


INFLUENCE  OF  OVERWORK  UPON  HEALTH      315 

Overwork,  coupled  with  depressed  vitality  or  other  influ- 
ences, may'give  rise  in  children  to  one  or  more  of  the  follow- 
ing troubles:  dyspepsia,  headaches,  nervous  derangements, 
chorea,  epilepsy,  neurasthenia,  backaches,  menstrual  dis- 
orders, and,  in  some  cases,  consumption.  On  the  other 
hand,  faulty  arrangement  of  seats  and  desks,  improper 
location  of  windows,  blackboards,  etc.,  may  cause  spinal 
and  other  physical  deformities,  defective  eyesight,  etc.  Of 
the  first  class,  even  where  the  amount  of  work  may  not 
seem,  or  may  not  really  be,  too  much  for  the  capacity  of 
the  child,  worry  about  rank  or  over  an  approaching 
examination  may  have  a  harmful  effect  upon  a  nervous 
temperament.  This  is  especially  so  if  the  examina- 
tions come  at  the  end  of  a  spring  term,  when  the  scholars 
are  all  more  or  less  worn-out  and  debilitated.  The  forcing 
process  should  be  avoided  as  far  as  possible,  and  if  grades 
are  to  be  given  at  all,  they  should  be  as  much  as  possible 
for  the  work  and  attendance  during  the  term,  and  not 
so  much  for  the  actual  work  done  at  examination  time. 

Moreover,  young  children  should  not  be  kept  in  school 
for  too  many  hours  in  the  day,  nor  should  school  be 
looked  upon  by  parents  as  a  place  to  which  to  send  chil- 
dren to  keep  them  out  of  the  way  and  from  mischief. 
Edwin  Chadwick  has  shown  that  a  child  from  five  to 
seven  years  can  only  attend  to  one  object  for  about  fifteen 
minutes;  one  from  seven  to  ten,  for  twenty  minutes; 
from  ten  to  twelve,  for  twenty-five  minutes,  etc.,  and  that 
the  length  of  individual  lessons  and  likewise  the  total 
day's  work  should  be  arranged  accordingly.  The  very 
early  years  of  school-life  should  be  given  to  inculcating 
correct  habits  of  attention  and  of  morals  and  to  training 
the  will  and  powers  of  concentration  and  observation, 
rather  than  to  the  teaching  of  any  special  knowledge. 

But  apart  from  the  physical  conditions  of  the  school- 
room and  postural  and  other  personal  habits  of  the  pupils, 
it  is  probably  the  work  attempted  outside  after  school 
hours,  and  not  the  actual  work  done  in  the  school,  that 
is  most  responsible  for  the  breaking  down  of  health, 


316  SCHOOL  HYGIENE 

especially  in  older  scholars.  In  Cleveland,  in  1881,  of 
186  girls  in  the  high  school,  29  per  cent,  of* those  who 
studied  less  than  two  hours,  70  per  cent,  of  those  study- 
ing from  two  to  four  hours,  93  per  cent,  of  those  study- 
ing from  four  to  six  hours,  and  100  per  cent,  of  those 
studying  over  six  hours  daily  out  of  school,  had  poorer 
health  while  at  school.  Of  these  same  girls,  the  per- 
centages of  those  whose  health  was  "very  poor  while 
at  school,"  dividing  them  the  same  way  as  regards  over- 
work, were  respectively  14,  40,  66,  and  100  per  cent. 
This  loss  of  health  was  attributed  by  the  parents  to  stair- 
climbing,  irregularity  of  meals,  worry  about  rank  and 
examinations,  etc.;  but  Goodell  says:  *'So  commonly  do 
I  find  ill  health  associated  with  brilliant  scholarship,  that 
one  of  the  first  questions  I  put  to  a  young  lady  seeking 
my  advice  is,  'Did  you  stand  high  at  school?'  "  Another 
writer  says:  "The  effects  of  anxiety  are  worse  than 
carrying  heavy  loads." 

In  fact,  one  of  the  leading  educators  of  the  country  has 
suggested  that  children  should  not  be  required  to  study 
reading,  writing,  or  drawing  before  the  age  of  ten  or 
eleven,  as  these  bring  into  action  and  use  the  close  appli- 
cation of  the  finer  sense  organs  and  faculties  which  are 
not  as  yet  fully  developed;  but  he  advises  that  the 
instruction  of  the  earlier  years  of  school-life  should  consist 
mainly  of  language  lessons,  history,  nature  studies,  and 
such  others  as  may  be  taught  orally  and  that  will  at  the 
same  time  develop  the  child's  powers  of  attention,  obser- 
vation, and  reasoning.  There  is  more  than  a  chance  that 
such  a  plan  of  instruction  would  not  only  secure  better 
results  from  the  teacher's  point  of  view,  but  that  it  would 
also  be  safer  for  the  scholar's  physical  organism. 

While  a  child  is  at  school  its  mind  should  not  be 
wearied  by  outside  tasks,  as  music  or  painting  lessons, 
nor  the  body  weakened  by  social  dissipations,  late  hours, 
and  indigestible  food.  Girls  are  more  susceptible  to  dis- 
turbances of  health,  and  are  more  subject  to  them,  because 
they  are  more  willing  to  undertake  extra  or  double  work 


ILL  HEALTH  DUE  TO  SCHOOL-LIFE  317 

than  boys,  and  because  they  are  more  ambitious  and  worry 
more  about  rank.  In  all  children  the  obtaining  of  good 
health  and  a  sound  constitution  is  of  the  first  importance. 
Youth  is  the  time  for  gaining  health,  not  for  losing  it; 
for  building  up  sound  bodies  and  constitutions,  not  for 
breaking  them  down,  and  school-life  should  always  have 
the  former  as  one  of  its  greatest  ends.  Of  what  use  is 
all  the  learning  one  may  gain  before  the  age  of  eighteen, 
if  there  be  no  strength  to  use  it  afterward  in  the  battle 
of  life? 

School-life  is  sometimes  responsible  for  dyspepsia  by 
interfering  with  the  regularity  of  meals,  the  children 
missing  the  mid-day  meal  and  having  to  depend  upon  a 
meagre  lunch,  often  of  sweets  and  indigestible  food.  This 
is  especially  important  when  the  rest  of  the  family  dine 
at  noon,  and  there  is  only  a  light  meal  served  in  the  even- 
ing. Again,  many  habitually  lose  their  breakfast  through 
fear  of  being  late,  or  else  bolt  the  food  without  masticat- 
ing it  and  gulp  down  hot  coffee  or  tea  before  starting  on 
a  run  for  school.  But  often  the  loss  of  appetite  is  due 
simply  to  lack  of  fresh  air  and  proper  exercise,  or  else 
to  the  nervous  condition  of  the  child,  which  is  sometimes 
such  as  to  interfere  with  almost  all  of  the  body  functions. 
Such  dyspepsias  are  to  be  treated  by  attention  to  the 
foregoing  points  rather  than  by  medicine. 

Headache  is  a  common  disturbance  among  school-chil- 
dren, and  may  be  due  to  any  one  of  several  causes,  among 
which  are  overwork — producing  irritability  and  disturb- 
ances of  cerejiral  circulation — indigestion,  bad  air,  eye- 
strain, etc.  /The  eyes  should  always  be  examined  when 
headaches  are  persistent,  and  any  defects  corrected  by 
proper  glasses^/  Associated  with  the  headaches,  frequent 
bleeding  from  the  nose  may  occur  and  should  not  be  over- 
look^, as  it  may  indicate  circulatory  disturbance. 
,^*NEye-strain  is  a  particular  evil  of  civilization,  and 
makes  its  first  appearance  in  school  when  the  scholar  tries 
to  accommodate  the  eye  to  the  short  range  which  reading 
requires,  but  for  which  the  eye  mechanism  is  not  well 


318  SCHOOL  HYGIENE 

adapted  by  nature."  "In  New  York  City  29.5  per 
cent,  of  79,069  children  examined  suffered  from  defective 
vision.  In  London  26  per  cent,  of  20,000  children  ex- 
amined by  eight  ophthalmologists  had  defective  vision, 
and  of  this  number  12.5  per  cent,  suffered  from  vision  of 
one-half  or  less.  In  Philadelphia  34  per  cent,  of  1156 
children  had  defective  vision,  and  of  this  number  6  per 
cent,  had  vision  of  one-half  or  less.  A  small  proportion 
of  this  number  only  is  fitted  with  glasses.  The  rest  suffer 
from  real  eye-strain."^ 

One  of  the  most  common  symptoms  of  nervous  derange- 
ment is  sleeplessness  or  restless  sleep,  and  this  condition 
should  give  warning  that  something  is  wrong.  Folsom 
says:  "I  doubt  whether  there  is  an  exaggerated  preva- 
lence of  manifest  or  well-marked  diseases  of  the  nervous 
system  among  school -children.  If  due  to  the  school-drill, 
my  impression  is  that  they  come  for  the  most  part  later 
in  life,  after  the  children  have  left  school,  and  because 
of  constitutions  weakened  during  school  years,  instead  of 
strengthened  as  they  should  be."  Children  subject  to 
chorea  or  epilepsy  should  not  attend  school,  not  only  for 
their  own  sake,  but  also  for  that  of  the  other  children,  who 
may  be  unduly  affected  by  their  nervous  manifestations. 
Such  children  should  be  educated  quietly  and  cautiously, 
with  proper  treatment  and  plenty  of  out-door  life.  Neuras- 
thenia or  general  break-down  may  occur,  usually  from 
overwork,  and  especially  among  young  women.  It  may 
come  on  unexpectedly  after  the  examinations  at  the  end 
of  the  term,  when  the  strain  and  excitement  are  removed. 

Menstrual  disorders  are  also  apt  to  occur  among  girls 
that  are  being  overworked  mentally,  and  we  ought  to 
remember  that  the  system  is  undergoing  a  heavy  strain 
at  the  time  this  function  is  developing.  Also,  for  certain 
young  women  rest  from  customary  work  is  necessary  at 
the  time  of  the  periodical  recurrence,  and  excuses  for 
absence  at  this  time  ought  to  be  freely  granted.    It  has 

1  Report  on  National  Vitality,  Fisher,  pp.  8,  74,  and  75. 


INFLUENCE  OF  SCHOOL-FURNITURE  319 

been  well  said  that  **  girls  get  through  as  much  work  as 
boys,  working  in  their  own  way." 

The  development  of  consumption  may  be  due  to  the 
school-life,  though  it  is  hard  to  say  how  frequently  this 
is  the  case.  Bad  air  and  overwork  are  both  important 
factors  in  its  production,  and  if  these  are  forced  on  under- 
fed or  predisposed  children  the  disease  may  be  provoked. 

Only  recently  have  we  realized  that  a  large  proportion 
of  the  cases  of  tubercular  infection  occur  in  early  life. 
The  greatest  mortality  from  this  disease  is  in  the  first 
two  years,  after  which  there  is  a  quiescent  period  for 
about  ten  years.  Then,  at  the  age  of  twelve  years  in 
girls  and  approximately  sixteen  in  boys  there  begins  a 
new  and  marked  increase  in  the  mortality  rate  which 
apparently  must  be  due  to  the  lighting  up  of  the  disease 
from  latent  foci  in  the  body  rather  than  to  a  new  infection 
from  without.  The  notable  recrudescence  of  the  disease 
at  these  ages  is  most  reasonably  to  be  attributed  to  the 
stresses  incident  to  pubertal  development  and  should  warn 
us  that  added  burdens  at  this  time,  whether  of  the  school 
or  home,  are  positively  inadvisable.^  "In  a  consumptive 
family  the  steadfast  rule  should  be  that  the  mind  be  wholly 
subservient  to  the  body's  welfare." 

The  main  cause  of  spinal  and  other  deformities  and 
defective  eyesight  is  apt  to  be  found  in  faulty  construction 
of  seats  and  desks,  improper  location  of  windows,  etc., 
though  excessive  work  or  strain  may  maintain  a  low 
vitality  and  act  as  a  predisposing  condition.  The  latter 
point  is  shown  by  the  fact  that  spinal  curvatures  are  more 
prevalent  in  those  especially  prone  to  weakness  of  the 
muscles,  as  women  and  girls.  But  no  desk  or  seat  will 
remove  original  weakness  of  muscle  as  the  one  important 
predisposing  condition,  and  children  cannot  be  made 
strong  by  supports.  "Spinal  curvature  is  not  only  a 
product  of  low  vitality,  but  does  harm  by  permanently 
fixing  vitality  at  a  low  standard." 

*  See  Hess:  Tuberculosis  in  Children,  Jour.  Am.  Med.  Assn.,  January 
n,  1919,  pp.  83-88. 


320 


SCHOOL  HYGIENE 


If 


Fig.  83.-Position  assumed  in  writing  with  the  desk  too  high.     (Pyle.) 


Fig.  84.— Position  assumed  in  writing  with  the  desk  too  low.     (Pyle.] 


INFLUENCE  OF  SCHOOL-FURNITURE  321 

Improperly  arranged  seats  and  desks  not  only  often 
cause  spinal  deformities,  but  also  help  to  develop  defective 
eyesight  by  causing  the  scholar  to  hold  the  book  too  near 
the  eyes  and  by  making  him  bend  his  head  so  that  the 
circulation  of  blood  is  impeded  and  ocular  congestion 
favored.  However,  no  seat  can  be  devised  in  which  a 
child  will  maintain  a  correct  or  "normal"  position  for 
any  but  a  short  time,  as  this  is  an  impossibility  for  young 
children;  but  the  aim  should  be  to  furnish  a  seat  in 
which  one  will  naturally  assume  the  correct  position  after 
having  temporarily  taken  any  other.  "Movement  is  a 
child's  way  of  resting;  rest  is  a  kind  of  work,  to  be  taught 
by  degrees."  Seats  should  have  backs  to  prevent  fatigue, 
but  a  comfortable  back  gives  support  to  the  lower  part 
of  the  spine  rather  than  to  the  shoulders  and  upper  part 
of  the  spine.  Many  foreign  authorities  advise  seats  with 
backs  only  high  enough  to  support  the  lower  part  of  the 
spine,  and  low  enough  for  the  scholar  to  rest  his  elbows 
upon  them  while  studying. 

The  following  points,  suggested  by  Lincoln,  are  worth 
noting :  "  (1)  The  chair  is  often  too  high  for  young  scholars. 
The  most  convenient  plan  may  be  to  provide  foot-stools. 
(2)  The  seat  from  back  to  front  ought  to  be  long  enough 
to  support  the  whole  thigh.  A  more  or  less  spoon-shaped 
hollow  in  the  seat  is  commonly  thought  desirable.  The 
curve  of  many  settees  is  such  as  to  produce  pain  at  the 
point  where  the  tuberosities  of  the  ischium  rest  on  the 
wood;  the  support  is  there  not  wide  enough.  (3)  Seats 
must  have  backs.  The  straight,  upright  back  reaching  to 
the  shoulders  is  bad;  a  straight  back,  slightly  tilted,  is 
not  bad.  American  seats  are  commonly  curved,  with 
curved  backs.  (4)  The  edge  of  the  desk  should  come 
up  to,  or  overlap,  the  edge  of  the  seat.  The  recognition  of 
this  fact  is  a  recent  discovery.  (5)  Most  of  our  best  desks 
are  too  high  relatively  to  the  seat,  doubtless  to  prevent 
the  pupil  from  stooping.  Something  is  gained  in  con- 
venience of  reading  by  this  plan,  but  it  interferes  with 
correct  positions  in  writing.  The  elbows,  hanging  freely, 
21 


322  SCHOOL  HYGIENE      ' 

should  be  only  just  below  the  level  of  the  lid."  For 
near-sighted  children  the  higher  desk  may  be  a  necessity 
in  writing;  if  the  desk  is  made  low,  a  portable  writing- 
stand  may  be  placed  on  top  of  it  when  necessary. 

Windows  on  only  one  side  of  a  large  school-room  may 
not  give  sufficient  light  for  the  desks  most  remote  from 
them.  Consequently  there  should  be  windows  on  two 
sides,  preferably  adjoining  ones,  of  large  school -rooms. 
The  windows  should  be  at  the  back  and  to  the  left  of  the 
scholar,  thus  giving  the  best  light  upon  the  desk  for 
either  reading  or  writing.  They  should  not  be  placed  in 
front  of  the  scholars,  as  the  continuous  glare  is  very  trying 
and  injurious  to  the  eyes.  They  should  extend  almost  to 
the  ceiling  and  have  square  tops,  to  admit  as  much  light 
as  possible.  In  some  cases  refraction  prisms  (Fig  82) 
may  be  used  to  advantage.  Blackboards  should  have  a 
dead-black  surface,  not  a  glossy  one,  and  should  be  on 
the  sides  of  the  room  on  which  there  are  no  windows. 
Walls  should  be  of  a  neutral  tint,  not  glaringly  white. 

In  some  cases  considerable  additional  diffusion  of  light 
may  be  secured  by  installing  a  series  of  light-colored  cur- 
tains corresponding  in  color  to  the  walls  of  the  room  and 
that  may  be  drawn  to  cover  the  blackboards  when  the 
latter  are  not  in  use. 


CONSTRUCTION  OF  SCHOOL-HOUSES. 

The  principles  already  given  as  to  ventilation,  heating, 
water-supply,  etc.,  apply  here  as  elsewhere.  From  1800 
to  2500  cubic  feet  of  fresh -air  should  be  supplied  to  each 
scholar  per  hour.  In  cold  weather  this  should,  of  course, 
be  satisfactorily  warmed.  The  air-ducts,  both  inlets 
and  outlets,  must  be  sufficiently  large  to  change  the  air 
without  causing  injurious  and  uncomfortable  draughts; 
and  these  ducts  should  be  as  short  and  free  from  bends 
as  possible,  or,  better,  the  rooms  should  open  into  the 
supply  and  exhaust  shafts  directly.  The  air  may  be 
warmed  either  by  steam  or  hot- water  coils  or  by  a  furnace, 


CONSTRUCTION  OF  SCHOOL-HOUSES  323 

though  preferably  by  the  former  to  avoid  "baking"  the, 
air,  and  also  preferably  by  the  indirect  system.  There  is 
no  objection  to  having  additional  heating  apparatus  in  the 
school-room,  provided  it  is  guarded  so  that  the  scholars 
may  not  be  accidentally  burned.  Any  system  that  will 
give  a  sufficient  supply  of  fresh  air  properly  heated  will 
of  necessity  be  more  expensive  than  the  old  way  of  not 
ventilating  at  all  except  by  opening  the  windows  at  recess 
time,  but  experience  shows  that  the  increase  in  expense 
is  not  so  very  great,  as  so  much  heat  is  lost  by  opening 
the  windows  in  this  way,  and  the  benefit  to  the  chil- 
dren more  than  compensates  for  the  additional  outlay.^ 
Country  schools  may  be  heated  by  stoves  surrounded  by 
sheet-iron  drums,  and  ventilated  with  fresh  air  from  with- 
out brought  in  near  the  bottom  of  the  stove.  (See  Figs. 
24  and  27.)  Passing  up  between  the  stove  and  drum  the 
air  is  warmed  and  gives  good  ventilation  without  chilling 
or  draught.  As  great  a  length  as  possible  of  stove-pipe 
should  be  exposed  in  order  to  get  the  full  benefit  of  the 
heat  from  it. 

The  Smead  system  of  ventilation  and  heating  has  been 
used  with  satisfaction  in  many  schools  throughout  the 
country.  In  this,  the  air  being  warmed  and  brought 
into  the  school -rooms  at  a  level  a  few  feet  above  the  floor, 
circulates  through  them  and  is  finally  withdrawn  through 
registers  at  the  floor  level,  whence  it  is  carried  under- 
neath the  floors  to  large  outlet  shafts  in  which  a  draught 
is  constantly  maintained.  In  this  way  thorough  diffusion 
and  changing  of  the  air  in  the  school-rooms  are  secured, 
and,  moreover,  the  floors  are  kept  warm  by  the  heat  from 
the  air  which  is  passing  beneath  them  and  which  would 
otherwise  be  wasted.     (Fig.  85.) 


'"Newton  reports  a  case  of  an  old,  unhygienic  school  building  in  a 
small  town  being  fitted  up  with  a  ventilating  system,  with  the  result 
that  the  cost  of  the  improvement  was  saved  in  a  short  time  in  salaries 
that  otherwise  would  have  been  paid  to  extra  teachers  for  taking  the 
place  of  those  made  sick  by  the  foul  air  in  the  building."  Report  on 
Human  Vitality,  Fisher,  p.  73. 


324 


SCHOOL  HYGIENE 


The  relative  size  of  the  school-room  is  of  importance. 
Each  pupil  should  have  about  twenty  square  feet  of  floor 
space,  and  as  there  should  not  be  over  forty  pupils  to 
the  room,  the  total  area  of  the  room  should  approximate 
800  square  feet.  The  length  of  the  room  will  depend  not 
only  upon  the  distance  both  teachers  and  pupils  can  be 
heard  distinctly,  but  at  which  the  scholars  can  see  the 
blackboards,  charts,  etc.,  distinctly,  and  school  manage- 
ment is  undoubtedly  easier  in  a  room  that  is  not  too  long. 
Experience   shows   that   ordinary  blackboard   writing   is 


Fig.  85. — Illustrating  the  Smead  system  of  ventilation. 


visible  at  twenty-nine  feet,  so  the  maximum  length  of  the 
room  will  be  about  thirty-two  feet,  this  allowing  for  an 
aisle  of  sufficient  width  at  the  rear  of  the  room. 

With  the  area  of  the  room  already  determined  as  indi- 
cated above,  this  length  necessitates  a  complementary 
width  of  twenty-five  feet,  a  dimension  that  is  also  in  a 
measure  governed  by  the  principle  that  the  school-room 
should  not  be  much  more  than  twice  the  height  of  the  top' 
of  the  windows,  which  in  turn,  should  extend  almost  to  the 
ceiling.    And  as  it  is  agreed  that  the  ceilings  for  rooms 


CONSTRUCTION  OF  SCHOOL-HOUSES  325 

of  this  size  and  purpose  should  be  about  twelve  or  thirteen 
feet  high,  the  width  mentioned  is  a  correct  one. 

Ample  cloak-rooms  should  be  provided  for  every  school; 
they  should  be  warm  and  well  ventilated  in  order  to 
secure  the  rapid  drying  of  the  garments  in  wet  weather, 
but  they  should  not  communicate  directly  with  the 
school-rooms  themselves,  if  it  can  be  avoided.  Provision 
should  also  be  made  for  readily  disinfecting  them,  and, 
in  fact,  the  whole  school  building  at  intervals  and  when- 
ever necessary. 

In  1897  at  Newcastle-upon-Tyne,  "the  experiment 
was  tried  of  closing  each  school,  where  scholars  were 
being  taken  ill,  for  a  few  hours  only,  long  enough  to 
allow  of  thorough  purification  and  the  sprinkling  of  the 
floors  of  class-rooms  with  disinfectants.  This  disinfection 
so  far  as  measles  was  concerned,  was  followed  by  the 
extinction  of  the  disease  in  question."^ 

The  school-house  should  be  on  dry  and  well-drained  soil, 
as  dampness  is  not  only  depressing  to  all  constitutions, 
but  is  also  an  important  factor  in  the  causation  of  phthisis 
and  strumous  diseases.  There  should  not  be  too  much 
shade  about,  and  as  many  rooms  as  possible  should  have 
sunny  exposures.  If  the  sunlight  is  annoying  during 
the  session,  it  may  be  excluded  by  inside  blinds  or  shutters, 
but  we  must  not  lose  sight  of  its  helpful  influence  in 
the  destruction  of  bacteria  and  purification  of  organic 
matters. 

Where  sunlight  is  scanty  or  it  is  difficult  to  illuminate 
the  school-rooms,  it  may  be  advantageous  to  furnish  one 
or  more  of  the  windows  with  some  form  of  the  diffusing 
and  refracting  prisms  already  described  (page  313),  thus 
giving  an  abundance  of  light  where  there  was  formerly  a 
deficiency,  and  materially  lessening  the  eye-strain  of  the 
scholars. 

Basements  of  school-houses  should  be  well  lighted  and 
dry,  and  should  be  kept  scrupulously  clean  that  moisture 

» American  Year-book  of  Medicine  for  1900,  pp.  54.3  and  544. 


'32G  SCHOOL  HYGIENE 

and  noxious  gases  may  not  be  drawn  into  the  rooms  above. 
If  properly  arranged  and  cared  for,  they  may  be  used  as 
play-rooms  in  stormy  weather  when  it  would  be  unwise  to 
send  the  scholars  out-of-doors. 

Open-air  Schools. — A  striking  innovation  of  recent  years 
is  the  open-  or  fresh-air  school,  the  first  being  established 
in  Germany  in  1904,  and  in  this  country,  in  Providence, 
R.  I.,  in  1908.  Since  then  others  have  been  opened  in 
many  American  cities,  and  "there  is  but  one  reason 
against  the  very  extensive  adoption  of  the  open-air  school 
— its  expense.  The  cost  per  capita  (about  $140  per 
annum)  is  four  or  five  times  that  of  the  per  capita  cost 
in  the  regular  school."^ 

As  Cornell  further  says:  "The  fresh-air  school  is  really 
a  sanatorium.  It  provides  not  only  free  air,  but  also 
nourishing  food,  enforced  rest,  warm  clothing,  individual 
teaching,  sympathetic  care,  and  medical  attention  which 
corrects  eye-strain,  adenoids,  decayed  teeth,  and  anemia. 
Naturally,  the  health  benefits  of  the  open-air  schools  are 
due  to  other  causes  as  well  as  the  fresh  air." 

Nevertheless,  the  results  obtained  are  most  striking 
and  have  served  to  increase  the  enthusiasm  of  the  advo- 
cates of  these  schools,  for  it  must  be  remembered  that 
the  pupils  in  them  have  been  selected  because  they  were 
poorly  nourished,  had  a  marked  tubercular  tendency, 
or  were  even  in  active  stages  of  tuberculosis.  The  gain 
in  weight,  strength  and  health,  increase  in  mental  activity 
and  progress  in  school  work  are  marked,  and  all  serve  to 
justify  these  schools  and  the  increased  cost  of  main- 
taining them. 

The  water-supply  should  be  free  from  impurities  and  as 
good  as  can  be  had.  In  the  country,  if  from  a  neighbor- 
ing farm-house  spring  or  well,  it  may  be  contaminated  by 
leakage  from  cesspools  and  barnyards.  Or  the  school 
water  may  be  taken  from  a  neighboring  spring  or  stream 
which  is  receiving  contamination  from  the  school-house 

^  Cornell's  Health  and  Medical  Inspection  of  School  Children,  p.  115. 


CONSTRUCTION  OP  SCHOOL-HOUSES  ,327 

cesspool  or  other  sources.  For  this  reason,  teachers 
should  be  taught  the  tests  for  chlorides  and  ammonia  and 
the  reason  for  making  them,  and  should  make  these  tests 
frequently.  If  cause  for  suspicion  arises,  the  use  of  the 
water  should  be  stopped  at  once. 


Fig.  86. — Type  of  sanitary  drinking  fountain  installed  in  schools  by 
placing  bubbling-cups  on  old  fixtures.    (Newmayer.) 

Water-closets  and  urinals,  where  in  use,  should  be  kept 
clean  by  a  competent  janitor,  and  the  principal  or  head- 
teacher  should  see  that  this  is  done.    In  the  country,  the 


328  SCHOOL  HYGIENE 

pail  or  earth-closet  system  should  be  substituted  for  the 
usual  privy-vault  or  cesspool,  and  it  should  be  the  duty 
of  some  one  apart  from  the  teacher,  regularly  appointed 
and  paid  by  the  school  directors  of  the  district,  to  see  that 
removals  are  made  at  proper  intervals;  the  teacher  should 
maintain  supervision  over  the  daily  condition  of  affairs. 
If  possible,  the  out-houses  should  be  connected  with  the 
school-house  by  covered  ways,  that  the  children  may  not 
be  exposed  in  inclement  weather;  but  these  ways  should 
be  open  or  else  constantly  ventilated  by  open  windows  on 
either  side.  Cesspools,  if  unavoidable,  should  be  at  least 
fifty  feet  distant,  and  should  drain  away  from  the  school- 
house. 

Though  approving  the  Smead  system  of  warming  and 
ventilation  for  school-rooms,  the  writer  cannot  say  that 
he  approves  that  modification  of  it  wherein  the  foul  air 
from  the  building  is  carried  over  the  fecal  excreta  of  the 
inmates  before  being  discharged  into  the  outlet  shafts  and 
carried  to  the  outer  air.  Though  the  method  rapidly 
desiccates  the  excreta  and  renders  it  inoffensive  to  the 
senses,  there  is  danger  of  the  dissemination  of  disease 
germs  as  well  as  a  departure  from  sanitary  principles  in 
the  method. 

Ample  provision  must  be  made  for  the  rapid  escape 
and  for  the  safety  of  scholars  and  teachers  in  case  of  fire 
or  panic.  Fire-drills  should  be  regularly  practised  in 
all  schools  of  two  stories  or  more,  and  presence  of  mind 
inculcated,  that  emergencies  may  be  met  with  safety. 
The  comfort  of  the  child  should  not  be  forgotten  in  the 
construction  of  the  school-house,  though  preservation  of 
health  is  the  main  aim. 

The  importance  of  ample  and  properly  equipped  school- 
and  other  playgrounds  for  children  should  also  be  em- 
phasized. Not  only  does  active  natural  play  in  suitable 
surroundings  do  far  more  for  the  physical  welfare  of  the 
body  and  the  invigoration  of  the  mind  than  formal 
gymnastics,  even  though  it  be  admitted  that  the  latter 
have  a  place  in  education,  but  the  former  also  aids  in 


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MEDICAL  INSPECTION  OF  SCHOOLS  329 

establishing  a  better  social  and  moral  status  among  the 
children  by  affording  natural  outlets  for  exuberant 
energy,  developing  self-restraint  and  consideration  of 
others,  keeping  the  boys  off  city  streets,  and  preventing 
thoughtless  or  malicious  mischief.  Such  playgrounds 
should,  wherever  possible,  have  competent  supervisors 
in  attendance  to  advise,  encourage,  and  instruct  those 
who  make  use  of  them,  as  well  as  to  prevent  disorder 
or  abuse  of  privileges. 

MEDICAL  INSPECTION  OF  SCHOOLS. 

As  certain  diseases  are  contagious,  it  is  necessary 
that  school  authorities  have  the  right  to  forbid  the 
attendance  of  such  persons  as  have  been  exposed  to  in- 
fection until  all  danger  of  transmitting  the  disease  to 
others  is  passed.  This  power  is  usually,  however,  exerted 
only  in  the  case  of  those  diseases  most  dangerous  to  life 
and  health,  though  the  stringency  of  the  regulations 
varies  at  different  places.  Smallpox,  scarlet  fever,  diph- 
theria, measles,  and  even  whooping-cough  should  always 
be  quarantined,  and  it  would  be  better  to  keep  children 
who  are  afflicted  with  minor  diseases  of  this  class  out  of 
school  till  all  danger  of  infection  is  over,  as  it  is  only  by 
rigid  measures  like  this  that  we  may  finally  be  able  to 
eradicate  those  maladies.  Considerable  evidence  now 
supports  the  view  that  there  is  a  marked  decrease  in  the 
prevalence  of  both  scarlet  fever  and  diphtheria  during  the 
summer  holidays  and  an  increase  in  the  fall  and  winter  due 
to  school  attendance.  But  Niven,  of  Manchester,  England , 
thinks  that  ''the  extreme  measure  of  closing  a  school  for 
scarlet  fever  is  rarely  called  for,  and  is  not  so  likely  to  be 
effectual  as  in  the  case  of  measles."^ 

Local  boards  of  health  should  make  and  enforce  rules 
looking  to  the  prevention  of  the  spread  of  the  graver 


*  See  Public  Health,   February.  June,    and    September,   1899;    also 
American  Year-book  of  Medicine  for  1900,  p.  538. 


330  SCHOOL  HYGIENE 

contagious  diseases,  and  should,  when  necessary,  close 
school-buildings  till  all  danger  is  past.  Lincoln  gives 
the  following  as  a  system  of  general  regulations:  ^'(1) 
Persons  affected  with  diphtheria,  measles,  scarlet  fever, 
or  smallpox  (varioloid)  must  be  excluded  from  the  schools 
until  official  permission  is  given  by  the  board  of  health 
for  their  readmission.  (2)  Persons  living  in  a  family  or 
house  where  such  a  case  occurs  are  also  excluded  until 
similar  permission  is  given.  (3)  This  permission  is  not  to 
be  given  until  sufficient  time  has  elapsed  since  the  occur- 
rence of  the  last  case  to  insure  safety,  nor  until  the 
premises  have  been  disinfected  under  the  direction  of  the 
board  of  health.  (4)  If  a  child  suffering  from  one  of  the 
above  diseases  attends  school,  the  premises  of  the  school 
must  be  disinfected  under  the  direction  of  the  board  of 
health  before  they  are  used  again.  (5)  Physicians, 
teachers,  school-officers,  and  school-children  knowing  of 
such  cases  of  disease  should  at  once  report  them  to  the 
board  of  health.  (6)  The  board  should  also  notify  the 
school  authorities  of  all  such  cases.  (7)  Notice  must  be 
sent  to  the  family  by  the  school  authorities,  acting 
conjointly  with  the  board  of  health." 

In  some  cities  a  card  catalogue  is  kept  of  all  the 
pupils  in  the  public  schools,  each  card  representing  a 
single  pupil  and  giving  full  information  concerning  his 
or  her  home,  parents,  brothers  and  sisters,  and  where  the 
same  are  employed,  or  are  attending  school.  In  case  of 
the  absence  of  any  pupil  for  three  days  or  more,  the  city 
board  of  health  must  be  notified  by  the  school  authorities 
and  the  scholar  is  not  permitted  to  return  to  school  until 
the  health  officers  are  satisfied  that  there  is  no  danger  of 
infection  and  have  so  notified  those  in  charge  of  the 
school.  Competent  and  wide-awake  truant  officers  are 
also  frequently  able  to  give  early  notice  of  the  occurrence 
of  infectious  disease  in  the  homes  of  school  children  so  that 
prompt  precautions  against  its  spread  may  be  instituted. 

The  following  table  of  the  periods  of  incubation  of  the 
respective  diseases  is  based  on  an  experience  of  over 


MEDICAL  INSPECTION  OF  SCHOOLS 


331 


twenty-eight  years  at  the    Rugby  School,  England,  by 
Clement  Dukes.^ 

AN   ANALYSIS  OF  THE    PERIODS  OF   INCUBATION. 


Name  of 
disease. 


Scarlet  fever 
Chicken-pox 
Mumps 
Rose-rash 
Measles    . 


Short- 

Long- 

est 

est 

period 

period 

of  incu- 

of incu- 

bation 

bation 

(days). 

(days). 

1 

9 

13 

19 

14 

25 

12 

22 

8 

14 

The  largest 

number 

occur  on  the 

following 

days. 


Second  and 

fourth 
Fifteenth 

Nineteenth 

Sixteenth 

Eleventh 


The  majority  of 
the  cases  arise 

between  the 
following  days. 


Percentage   re- 
ferring to  pre- 
vious    column, 
\  e.  g..  59  per  ct. 
i  occur    between 
I  the  second  and 
fourth  days. 


Second   and 

fourth 
Fourteenth    and 

seventeenth 
Seventeenth  and 

twentieth 
Fourteenth    and 

seventeenth 
Ninth     and 

twelfth 


10  out  of  17  » 

59  per  cent. 
24  out  of  36  = 

66  per  cent. 
50  out  of  69  = 

72.46  per  ct. 
31  out  of  40  =« 

77.5  per  cent. 
18  out  of  24  = 

75  per  cent. 


Another  authority  gives  the  following: 


TABLE  OF  THE  ERUPTIVE  FEVERS. 


Name. 


Chicken-pox 
Erysipelas 
Measles  . 
Rotheln  . 
Scarlatina' 
Smallpox 
Typhoid  fever 


Incubation.         Day  of  rash. 


4  to  14  days 

1  to    5  days 

10  to  12  days 

7  to  17  days 
1  to  21  days 

8  to  14  days 
10  to  21  days 


Second  or  third 
First  to  third 
Fourth 

First  or  second 
Second 

Third  or  fourth 
Seventh  to four- 
teenth 


Duration  of 

eruption. 

4  to 

8  days 

4  to 

8  days 

3  to 

5  days 

1  to 

3  days 

4  to  10  days   j 

16  to  25  days 

Duration  of 
disease. 


1  to  2  weeks 

1  to  3  weeks 
10  to  14  days 

4  to  7  days 

2  to  3  weeks 

3  to  5  weeks 
3  to  4  weeks 


Children  having  had  one  of  the  above-named  diseases 
may  return  to  school  with  safety  after  the  following 
periods,  provided  there  has  been  a  thorough  disinfection 


1  Lancet,  April  29,  1899. 

"^  In  regard  to  the  discrepancy  in  the  above  tables  respecting  the 
incubation  of  scarlet  fever  (from  one  to  twenty-one  days),  the  writer 
believes  the  shorter  period  to  be  more  nearly  correct;  also  that  the 
incubation  period  of  measles  is  frequently  less  than  ten  days,  as  is  occa- 
sionally that  of  typhoid  fever.  Relapses  may  extend  the  duration  of 
typhoid  fever  to  much  more  than  four  weeks. 


332  SCHOOL  HYGIENE 

of  their  homes  and  clothing:  "Scarlet  fever,  six  weeks 
from  the  date  of  rash,  provided  desquamation  and  cough 
have  ceased.  Smallpox  and  chicken-pox,  when  every  scab 
has  fallen.  Whooping-cough,  after  six  weeks  from  com- 
mencement of  whooping,  providing  the  characteristic 
spasmodic  cough  and  whooping  have  ceased,  or  earlier 
if  all  cough  has  passed  away.  Diphtheria,  not  less  than 
three  weeks,  if  convalescence  is  completed;  there  being 
no  longer  any  form  of  sore  throat  nor  any  kind  of  dis- 
charge from  the  throat,  nose,  eyes,  ears,  etc.,  nor  any 
albuminuria."  Wherever  possible,  a  bacteriological  ex- 
amination of  the  nose  and  throat  secretions  of  a  scholar 
that  has  had  diphtheria  should  be  made  from  time  to 
time,  and  his  return  to  school  should  only  be  permitted 
when  two  successive  examinations  no  longer  show  the  pres- 
ence of  the  specific  organism  in  the  secretions  mentioned. 
Rules  and  regulations  like  the  above,  when  promulgated, 
"should  have  the  force  and  authority  of  law,  and  should 
be  enforced,  if  necessary,  by  the  entire  power,  including 
school  ofiicers,  etc.,  of  the  State."^ 

Boarding-schools  and  similar  institutions  should  have 
an  infirmary  where  contagious  diseases  may  be  isolated, 
and  those  in  charge  should  make  that  isolation  from  other 
scholars  and  inmates  as  complete  as  possible.  At  the 
beginning  of  a  term  it  may  be  well  to  subject  scholars 
who  have  been  exposed  to  contagion  to  a  postponement 
of  attendance  until  the  probable  period  of  incubation  for 
the  special  disease  is  passed,  the  period  dating  from  the 
time  of  exposure  and  subsequent  disinfection  of  clothing, 
etc.  With  the  above  precautions  it  will  rarely  be  neces- 
sary to  close  a  school  unless  a  disease  is  markedly  epi- 
demic and  malignant. 

It  is  to  be  hoped  that  we  shall  soon  have  a  means  of 
inoculating  persons  against  all  contagious  diseases,  as  we 

^  Recent  investigations  have  shown  that  the  purulent  discharge  from 
the  ear  that  so  often  follows  attacks  of  measles  and  scarlet  fever,  and 
less  frequently,  of  diphtheria,  may  be  highly  infectious  and  a  positive 
agent  in  disseminating  the  respective  maladies.  Consequently  children 
should  be  excluded  from  schools  until  this  sequel  of  disease  as  well  as 
others  has  entirely  disappeared. 


MEDICAL  INSPECTION  OF  SCHOOLS 


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334  SCHOOL  HYGIENE 

now  do  against  smallpox.  At  present,  boards  of  health 
and  school  boards  should  insist  on  the  vaccination  of  all 
school-children.  In  Illinois,  from  1880  to  1883,  the 
deaths  from  smallpox  among  unvaccinated  children  were 
48  per  cent,  of  those  incurring  the  disease;  among  the 
vaccinated,  only  0.9  per  cent.  In  Philadelphia  all  who 
desire  it  are  vaccinated  free  of  charge  by  the  vaccine 
physicians,  and  it  is  compulsory  for  all  school-children. 

Lincoln  has  also  suggested  that  further  regulations 
similar  to  the  following  should  be  in  force  in  every  school 
district:  "Every  child  entering  the  public  schools  must 
show  a  certificate  from  some  reputable  physician,  giving 
name,  age,  residence,  approximate  date  of  vaccination, 
date  of  examination,  result  of  examination;  the  last  two 
to  be  of  the  physician's  own  knowledge.  The  fact  of 
vaccination  must  be  entered  on  the  school  record  and  on 
lists  for  promotion  and  transfer.  The  school  authorities 
shall  annually  report  the  number  of  those  not  protected 
to  the  State  Superintendent  of  Education.  School 
authorities  may  order  the  exclusion  of  non-protected 
persons,  after  sufficient  notice,  where  they  think  the 
measure  required  for  the  public  health.  Re  vaccination 
at  the  age  of  fifteen  may  be  required  under  similar  cir- 
cumstances. Those  unable  to  pay  should  be  furnished 
with  free  vaccination  by  the  school  authorities.  A  phy- 
sician's certificate  of  protection  by  a  previous  attack  of 
smallpox  is  equivalent  to  a  certificate  of  vaccination." 

Contagious  ophthalmia  is  a  disease  often  prevalent  in 
charitable  and  educational  institutions  and  occasionally 
in  primary  schools,  and  requires  great  care  to  prevent  its 
invasion  and  spreading,  as  well  as  to  effect  a  cure.  Those 
afflicted  with  it  should  be  quarantined  until  there  is  no 
further  discharge  or  till  the  granulations  on  the  inner 
surface  of  the  eyelids  have  disappeared.  Enfeebled  health 
and  poor  and  insufficient  food  favor  its  development,  but 
the  chief  means  of  contagion  is  by  the  use  of  the  same 
wash-basins  and  towels  by  a  number  of  children. 

Other  diseases  that  may  be  transmitted  in  much  the 
same  way  are  chronic  conjunctivitis   ("granular  lids") 


MEDICAL  INSPECTION  OF  SCHOOLS  335 

and  those  due  to  fungous  and  other  parasites,  as  the  tineas 
("ringworm  of  the  scalp  or  face")>  pediculosis,  etc.,  all 
of  which  may  be  transmitted  by  an  interchange  of  hats 
or  caps  or  other  garments. 

School  children  should  not  be  allowed  to  attend  the 
funerals  of  companions  dead  of  a  contagious  disease,  nor 
should  funerals  be  allowed  to  take  place  from  school- 
houses  under  any  circumstances,  owing  to  the  effect  on 
the  thoughts  and  sensibilities  of  nervous  children. 

One  of  the  most  noteworthy  developments  in  the  line 
of  modern  public  health  work  is  that  of  school  medical 
inspection.  Not  only  are  the  troubles  of  ailing  or  defective 
pupils  discovered,  the  attention  of  parents  directed  thereto, 
corrections  of  the  same  brought  about  and  the  spread  of 
infectious  diseases  prevented;  but  the  general  welfare 
of  the  public  at  large  is  enhanced  by  the  physical,  mental 
and  moral  improvement  in  the  youthful  portion  of  the 
population  that  is  an  inevitable  result  of  the  work.  As 
an  indication  of  the  importance  and  extent  of  such  work 
in  a  large  city,  the  records  in  Philadelphia  for  the  calendar 
year  1913  show  a  total  of  158,974  notices  by  school 
inspectors  to  parents  concerning  physical  defects  in  the 
children,  of  which  about  75,000  were  for  troubles  requiring 
treatment  by  physicians,  and  about  64,000  were  because 
of  carious  teeth  requiring  dentist's  attention.  In  the 
same  period  almost  3,000  contagious  and  14,000  parasitic 
diseases  were  reported. 

The  following  table  indicates  the  nature  of  the  physical 
defects  recommended  for  treatment: 


Eye-strain 17,506 

Other  eye  cases 7,595 

Nose  and  throat  defects 34,522 

Ear  defects  and  diseases                    2,261 

Diseases  of  teeth 64,238 

Orthopedic  defects 2,706 

Poor  nutrition 2,464 

Functional  nervous  diseases 1,111 

Heart  disease 872 

Skin  disease  (mostly  unimportant)        ....  19,833 

Accidents,  acute  illness 2,208 

Miscellaneous 3,608 


336  SCHOOL  HYGIENE 

The  important  part,  however,  of  the  report  from  which 
the  above  figures  are  taken  is  that  in  the  first  seven  months 
of  the  year  43  per  cent,  of  the  defects  then  reported  had 
been  corrected  subsequent  to  the  issuance  of  the  inspector's 
notices,  the  proportion  of  defects  corrected,  classified 
according  to  the  nature  of  defect,  being  as  follows: 

Per  cent. 

Eye 36.0 

Ear 61.0 

Nutrition 52.3 

Heart    . '   .   53 . 8 

Nose  and  throat 29 . 9 

Teeth 27.5 

Orthopedic 37.8 

"Medical  inspection  in  our  schools  returns  large  divi- 
dends on  small  investments.  Jensen  has  shown  that  the 
cost  of  a  school  dental  clinic  in  Germany  is  only  one 
mark  per  year  per  child.  The  cost  saved  must  be  very 
many  times  this  sum."  "Cronin,  of  New  York,  main- 
tains that  in  a  school  population  of  650,000,  30  per  cent, 
of  the  children  were  from  one  to  two  years  behind  their 
proper  class.  Ninety-five  per  cent,  of  these  children 
were  so  principally  because  of  defects  of  eye,  ear,  nose, 
or  throat,  which  could  easily  be  detected  and  remedied 
through  effective  medical  inspection.  Experiments  at 
home  and  abroad  have  proved  beyond  any  doubt  that  the 
majority  of  children  of  this  sort,  when  given  proper  medical 
treatment,  improve  markedly  in  intellect  and  general 
conduct.  The  State  attempts  to  educate  these  children, 
but  its  efforts  are,  to  a  large  extent,  wasted.  Osier  calcu- 
lated that  in  the  special  city  to  which  reference  has  been 
made  there  was,  on  account  of  a  lack  of  medical  super- 
vision of  educational  work,  a  yearly  financial  loss  of 
$1,666,666;  of  course,  the  loss  which  came  from  moral 
deviation  due  to  defective  physical  functioning  was  of  far 
greater  importance.  He  also  said  recently,  in  effect,  that 
he  considered  it  of  greater  importance  to  the  nation  that 
the  question  of  sound  teeth  be  intelligently  considered 


MEDICAL  INSPECTION  OF  SCHOOLS  337 

than  that  the  consumption  of  alcohol  be  restricted,  im- 
portant as  the  latter  problem  is."^ 

1  Report  on  National  Vitality,  Fisher,  pp.  123  and  173. 

Readers  especially  interested  in  the  many  and  various  phases 
of  School  Hygiene  are  advised  to  consult  Cornell's  Health  and 
Medical  Inspection  of  School  Children  (F.  A.  Davis  Co.  New- 
mayer's  Medical  and  Sanitary  Inspection  of  Schools  (Lea  & 
Febiger),  Terman's  Hygiene  of  the  School  Chi'.d  (Houghton, 
Mifflin  &  Co.);  Dresslar's  School  Hygiene  (Macmillan  Co.) 
and  Rowe's  Physical  Nature  of  the  Child  (Macmillan  Co.)  as 
sources  of  authoritative  and  abundant  information,  and  for 
details  that  may  not  be  included  in  the  limits  of  a  single 
chapter. 


22 


CHAPTER  X. 
DISINFECTION. 

As  has  been  stated,  disinfection  is  that  part  of  pro- 
phylaxis which  has  to  do  with  the  destruction  or  modifi- 
cation of  the  exciting  causes  of  disease,  and  we  may 
accordingly  define  a  disinfectant  as  "an  agent  capable  of 
destroying  the  infective  power  of  infectious  material,"  or, 
as  "an  agent  which  brings  about  the  destruction  of 
bacteria  in  general,  and  more  particularly  of  those  that 
act  as  the  exciting  causes  of  disease."^  Consequently,  as 
with  our  present  knowledge  we  are  practically  limited  in  the 
use  of  disinfection  to  the  infectious  diseases  only,  a  disin- 
fectant must  also  be  a  germicide.  Theoretically,  it  should, 
also  have  the  power  of  destroying  the  poisonous  properties 
of  the  toxins  which  the  disease  germs  produce  arfi'd 
which  create  the  characteristic  symptoms  of  the  specific 
diseases,  but  whether  all  efficient  disinfectants  have  this 
power  is  by  no  means  proved;  nor  is  it  altogether  essential 
that  they  do  have  it,  since  by  killing  the  germs  we  check 
the  further  production  of  the  toxins;  and  disinfectants 
are  mainly  used  not  so  much  to  cure  or  arrest  the  progress 
of  a  disease  in  a  patient  as  to  prevent  its  incurrence 
by  others. 

In  a  popular  sense,  the  term  disinfection  is  given  a 
wider  meaning  than  is  indicated  above,  one  including  not 
only  the  use  of  antiseptics  and  deodorants,  but  often 
also  the  actual  removal  of  filth  and  all  matters  favorable 
to  the  growth  or  spread  of  disease  germs,  which  is,  strictly 
speaking,  a  matter  of  sanitation.  It  is  needless  to  say 
that  the  latter  work  may  be  part  of  the  prescribed  duties 
of  a  disinfector,  but  it  is  not  one  of  the  essential  functions 
of  a  disinfectant. 

1  Harrington,  Practical  Hygiene,  p.  488. 
(338) 


DISINFECTANTS,  ANTISEPTICS  AND  DEODORANTS  339 

It  will  be  well  here  to  make  the  distinction  between 
disinfectants  and  antiseptics  and  deodorants,  as  the  terms 
are  often  erroneously  used  interchangeably,  and  as  there  is 
a  common  belief  that  whatever  is  a  deodorant  or  an  anti- 
septic is  also  a  disinfectant.  An  antiseptic  is  an  agent 
that  retards  or  arrests  bacterial  grow^th  and  the  conse- 
quent production  of  toxins  or  ptomains,  though  it  does 
not  necessarily  kill  the  microorganisms  themselves;  and 
though  some  antiseptics  are  germicidal,  others  are  not, 
and  therefore  as  a  class  they  cannot  be  considered  or 
used  as  disinfectants.  But,  on  the  other  hand,  "agents 
which  kill  bacteria  in  a  certain  amount  prevent  the  mul- 
tiplication of  the  latter  in  culture-fluids  when  present  in 
quantities  considerably  less  than  are  required  to  destroy 
vitality."  So,  a  diluted  germicide  may  act  as  an  anti- 
septic and  may  be  used  therefor.  For  instance,  chlorin- 
ated lime,  which  is  a  good  disinfectant  in  solutions  of 
proper  strength,  may  arrest  further  bacterial  grow^th  or 
action  in  a  mass  of  sew^age  or  filth  and  prevent  the  latter 
acting  as  a  culture-medium  for  disease  germs,  even 
though  the  agent  be  totally  inadequate  in  quantity  to  kill 
all  the  microorganisms  present.  In  the  same  way,  it 
may  act  as  a  deodorant — which,  by  the  way,  is  an  agent 
that  simply  removes  or  destroys  offensive  odors,  and  is 
not  necessarily  either  a  disinfectant  or  an  antiseptic — both 
by  checking  the  further  action  of  saprophytic  bacteria 
and  the  consequent  formation  of  putrefactive  odors,  and 
by  actually  decomposing  and  oxidizing  those  of  the  latter 
already  formed. 

In  practical  disinfection  it  is  also  w^ell  to  remember 
that  while  masses  of  dead  organic  matter  may  not  in  some 
cases  contain  disease  germs,  and  may  be  even  hostile  to 
them,  in  general  the  reverse  of  this  is  more  likely  to  be 
true,  and  decaying  matter  often  furnishes  a  good  field  for 
the  increase  of  pathogenic  organisms.  Moreover,  the 
noxious  gases  given  off  to  the  air  and  the  poisonous 
products  added  to  a  drinking-water  from  such  masses 
may  also  do  much  harm  by  depressing  the  system,  lower- 


340 


DISINFECTION 


ing  the  vitality,  and  acting  as  predisposing  conditions  to 
the  incurrence  of  such  filth-diseases  as  cholera,  yellow 
fever,   typhoid   and  typhus    fever,   diphtheria,   etc.;    so 


/yMRMOVfrr 


•  S.AMiTj^Tioisr  Good        OFair  <BBj\d 

Fig.  87. — Diphtheria  and  poor  sanitation.  Chart,  showing  cases 
which  originated  apparently  spontaneously  and  the  grade  of  sanitation 
of  each  infected  dwelling.  (From  Cornell's  Health  and  Medical  Inspec- 
tion of  School  Children.) 


THOROUGHNESS  IN    DISINFECTION  ESSENTIAL     341 

when  time  or  opportunity  does  not  permit  of  the  removal 
of  such  dangerous  accumulations,  their  power  for  harm 
should  be  checked  permanently,  or  at  least,  temporarily 
by  the  use  of  suitable  disinfectants  or  antiseptics. 

But  when  we  are  actually  dealing  with  disease  germs, 
disinfection,  to  be  trustworthy,  must  be  carried  out  to 
the  best  of  our  ability  with  the  means  at  our  command 
and  with  strict  attention  to  the  minutest  details.  "There 
can  be  no  partial  disinfection  of  infectious  material; 
either  its  infectious  power  is  destroyed  or  it  is  not.  In 
the  latter  case  there  is  a  failure  to  disinfect."  This  is 
because  the  undestroyed  living  bacteria  still  have  the 
power  of  reproduction,  and  may,  within  a  very  short  time 
under  favorable  circumstances,  equal  or  even  exceed  the 
number  that  was  present  before  the  unsuccessful  attempt 
at  disinfection  was  made.  In  fact,  our  aim  in  such  pro- 
phylaxis must  always  be  "to  interrupt  all  possible  paths 
of  disease  conveyance,  and  to  exterminate  the  causal 
agent." 

The  knowledge  as  to  the  efficacy  of  any  substance  as  a 
disinfectant  is  obtained  from  the  accumulated  experiences 
of  practical  sanitarians  and  from  experiments  on  suscep- 
tible animals  and  in  culture-media  in  which  infectious 
matter  is  treated  with  that  substance.  The  knowledge 
gained  must  stand  the  test  of  scientific  deduction,  and  a 
substance  is  not  a  disinfectant  simply  because,  in  one 
given  case,  infection  did  not  occur  after  its  use.  To  be 
of  value  the  deductions  must  be  made  from  considerable 
accumulated  and  practical  experience.  "Negative  evi- 
dence should  be  received  with  great  caution;"  but  if  the 
experience  of  practical  sanitarians  is  confirmed  by  careful 
culture  and  inoculation  experiments,  our  knowledge  of 
the  value  of  any  agent  becomes  more  definite  and  our 
practical  work  more  exact.  From  such  inoculations  and 
experiments  it  has  been  found  that  the  infectious  germs 
of  different  diseases  differ  in  their  power  to  resist  the 
different  disinfectants;  but  nevertheless  it  may  be  stated 
that  "  in  the  absence  of  spores,  a  disinfectant  for  one  is  a 


342  DISINFECTION 

disinfectant  for  all . "  Consequently,  we  are  able  to  simplify 
and  classify  the  agents  at  our  disposal  and  to  make  more 
effectual  use  of  them. 

Some  agents  that  are  powerful  against  all  other  organ- 
isms completely  fail  to  destroy  the  vitality  of  spores, 
and  thus  our  list  of  disinfectants  available  in  all  cases  is 
still  further  reduced.  In  the  case  of  a  disease  germ  that 
does  not  produce  spores,  as  that  of  diphtheria  or  typhoid 
fever,  agents  may  be  used  that  are  powerless  against 
spores,  but  in  doubtful  cases  only  those  should  be  used 
that  have  the  power  of  spore  destruction. 

We  may  classify  the  disinfectants  of  which  we  com- 
monly make  practical  use  as  either  thermal  or  chemical, 
not  forgetting,  however,  the  influence  of  sunlight  or  light 
from  artificial  sources,  especially  that  which  is  rich  in 
ultra-violet  radiations.  As  Duclaux  has  said,  "the  sun 
(light)   is  the  cheapest  disinfectant  known." 

There  may  also  be  a  mechanical  sterilization,  as  in  the 
separation  of  microorganisms  from  a  liquid  by  filtration 
or  sedimentation,  or  by  their  physical  removal  from  very 
smooth  articles  by  wiping,  or  from  the  human  skin  by 
thorough  scrubbing  and  washing.  The  efficiency  of  the 
latter  depends  on  the  smoothness  of  the  person's  skin, 
the  extent  of  exposure  to  pathogenic  germs,  and  especially 
upon  the  care  and  thoroughness  with  which  the  cleansing 
process  is  accomplished. 

Lastly,  certain  secretions  and  tissues  in  the  body  which 
have  the  power  of  destroying  infective  matters,  giving 
each  person  more  or  less  immunity  against  certain  diseases, 
may  be  termed  physiological  disinfectants. 

THERMAL  DISINFECTANTS. 

■  Of  the  thermal  disinfectants, /ire  is  the  most  efficacious, 
as  it  destroys  all  organic  matter,  but  it  can  only  be  used 
to  disinfect  non-combustible  articles  or  those  that  are 
of  little  value  and  that  cannot  be  safely  disinfected  in 
any  other  way.     For  instance,  as  it  will  usually  cost 


THERMAL  DISINFECTANTS 


343 


more  than  they  are  worth  thoroughly  to  disinfect  by  other 
methods  used  dressings  from  wounds  or  old  mattresses 
that  have  been  used  in  infectious  cases,  it  is  best  to  burn 
them. 

All  things  considered,  steam  is  probably  the  most  prac- 
tically efficient  disinfectant,  as  it  is  cheap,  easily  used  and 
manipulated,  and  is  less  liable  to  injure  the  articles  to  be 
disinfected.  We  employ  it  under  pressure,  when  its  tem- 
perature is  correspondingly  increased,  or  in  the  streaming 
state   (live  steam),  the  latter  being  as  efficient  as  the 


Fig.  88. — Steam  sterilizer  for  small  ^articles. 


former,  but  sometimes  requiring  a  little  longer  time.  For 
instance,  steam  at  240°  F.  is  said  to  kill  the  most  resistant 
spores  very  quickly,  and  streaming  steam  at  212°  F.  will 
produce  the  same  effect  within  thirty  to  forty  minutes. 
In  fact,  under  very  favorable  conditions,  probably  few,  if 
any,  of  the  ordinary  pathogens  can  withstand  the  tem- 
perature of  boiling  water  (212°  F.)  longer  than  a  few 
minutes,  but  it  is  always  wise  to  employ  sufficient  time 
and  heat  to  remove  any  possibility  of  doubt  or  danger. 
One  should  also  remember  that  for  surface  disinfection 
streaming,  saturated  steam  is  relatively  much  more  efficient 


344  DISINFECTION 

than  superheated  steam,  on  account  of  the  great  liberation 
of  latent  heat  when  the  former .  condenses,  and  possibly 
because  the  latter  tends  to  dry  rather  than  moisten  the 
organisms  and  thus  render  them  harder  to  disinfect. 
As  a  sanitary  precaution  and  to  prevent  the  spread  of 
epidemics,  special  apparatus  for  disinfecting  large  articles 
by  steam  is  now  or  doubtless  soon  will  be  established  in 
every  large  city  and  hospital  by  the  municipal  authorities 
and  others. 


Fig.  89. — Steam  disinfecting  chamber  for  clothing,  bedding,  and  other 
large  articles. 

In  steam  sterilization,  as  with  all  other  disinfectants, 
the  aim  must  be  to  bring  the  germicidal  agent  into  contact 
with  every  part  of  the  infected  matter;  in  other  words, 
to  secure  thorough  penetration.  The  size  and  compact- 
ness of  the  articles  to  be  sterilized  accordingly  govern  in 
part  the  duration  of  their  treatment  by  the  steam.  Steam 
under  pressure  is,  of  course,  more  penetrating  than  live 
steam,  and  is  especially  expeditious  when  the  apparatus 
is  so  arranged  that  the  air  can  be  exhausted  from  it  and 
a  vacuum  created  in  the  interstices  of  the  articles  to  be 
disinfected  before  the  steam  is  introduced. 


THERMAL  DISINFECTANTS  345 

In  the  large  sterilizers  constructed  for  hospital  or 
municipal  use  every  precaution  is  taken  to  prevent  the 
reinfection  of  articles  after  they  have  been  once  sterilized. 
The  goods  enter  the  apparatus  at  one  end,  and  after  the 
treatment  are  taken  from  it  at  the  other  end,  being 
handled  and  delivered  to  their  owjiers  or  destination  by  an 
entirely  different  group  of  employes  and  conveyances  than 
those  concerned  with  them  before  the  disinfection.  The 
apparatus  is  built  into  a  closed  partition,  which  entirely 
separates  the  two  parts  of  the  disinfecting  building  and 
prevents  any  transmission  of  germs  from  the  infected  to 
the  disinfected  side,  especially  as  the  doors  of  the  sterilizer 
are,  or  should  be,  so  arranged  that  they  cannot  both  be 
open  at  the  same  time. 

Boiling-point  of  Water  Under  Steam-pressure. ' 

Steam-pressure  Boiling  temperature, 

(pounds).  (F.)  (C.) 

0 212°       100.0° 

5 228°       109.0° 


10 240°  115.5° 

15 251°  121.5° 

20 260°  126.5° 

40 287°  141.5° 


In  the  absence  of  spores,  bacteria  are  killed  by  hot 
water  even  below  the  boiling-point,  and  it  is  safe  to  say 
that  boiling  for  ten  or  fifteen  minutes  will  kill  all  known 
disease  germs,  especially  if  from  1  to  2  per  cent,  of  wash- 
ing soda  or  a  little  common  salt  (sodium  chloride)  be 
added  to  the  water;  although  spores  of  certain  harmless 
bacilli  are  said  to  have  resisted  boiling  for  several  hours. 
The  addition  of  soda  also  prevents  the  rusting  of  iron  or 
steel  instruments,  but  is  likely  to  cause  erosion  of  alumi- 
num articles.  In  the  absence  of  chemical  disinfectants, 
boiling  water  may  be  used  to  disinfect  excreta,  etc.;  and 

*  McFarland  and  Babcock,  in  Cohen's  System  of  Physiologic  Thera- 
peutics, vol.  V,  p.  201. 


346  DISINFECTION 

all  clothing  worn  by  the  sick  or  the  attendants  upon  the 
sick  should  be  well  boiled  before  using  again,  whether 
other  disinfectants  are  employed  or  not. 

Dry  heat  is  far  less  penetrating  and  less  effective  than 
moist,  and  must  accordingly  be  used  at  much  higher 
temperatures  and  for  a  longer  time.  At  300°  F.  dry  air 
will  require  at  least  three  or  four  times  as  long  to  do  what 
steam  at  212°  or  220°  F.  will  do,  and,  moreover,  at 
such  high  temperatures  it  is  very  apt  to  injure  clothing 
or  other  organic  materials  exposed  to  it  for  so  long  a  time 
as  is  necessary.  Consequently,  it  is  only  to  be  used  to 
disinfect  articles  that  would  be  injured  by  moisture  or 
chemicals,  and  even  then  it  is  better  to  employ  the  "frac- 
tional" method  of  disinfection — i.  e.,  exposure  to  high 
temperatures  for  short  periods  only,  but  for  a  number  of 
times,  with  sufficient  intervals  between  the  exposures  to 
allow  the  development  of  any  spores  that  may  possibly  be 
present. 

Contrary  to  the  popular  opinion,  cold  is  not  a  positive 
germicide,  or  at  best  is  but  a  slowly  acting  one.  Typhoid 
germs  have  been  frozen  for  more  than  one  hundred  days 
without  all  of  them  losing  their  power  for  harm,  and 
various  microorganisms  have  withstood  the  temperature 
of  liquid  air— below  — 300°  F. — for  several  hours  or  days. 
However,  freezing,  especially  if  intermittent,  is  harmful  to 
the  growth  of  bacteria,  and  they  gradually  decrease  in 
number  in  frozen  material. 

In  this  connection  it  is  not  out  of  place  to  refer  again 
to  the  germicidal  power  of  light,  especially  sunlight,  and 
to  its  value  as  an  adjunct  in  the  disinfecting  of  rooms, 
clothing,  etc.  It  is  an  agent  that  may  be  used  progressively 
and  efficiently  in  the  sick-room  throughout  the  course  of 
an  infectious  disease;  and  psychically,  as  well  as  other- 
wise, adds  to  the  cheer  and  comfort  of  the  patient  rather 
than  to  increase  his  discomfort,  as  does  the  use  of  most 
other  means  to  the  same  end. 


CHEMICAL  DISINFECTANTS  347 


CHEMICAL  DISINFECTANTS. 

Regarding  the  chemical  disinfectants,  it  must  be  re- 
membered that  it  requires  a  certain  amount  of  each  to 
disinfect  a  given  quantity  of  bacteria,  and  also  that, 
with  all  disinfectants,  time  is  an  important  element, 
as  none  act  absolutely  instantaneously.  Heat,  however, 
facilitates  and  increases  the  rapidity  of  action  of  the 
chemical  disinfectants. 

Another  caution  to  be  observed  is  that  the  disinfectant 
should  always  be  of  sufficient  strength  in  the  mixture  with 
infected  material.  For  example,  if  a  disinfectant  is  only 
efTective^in  1  per  cent,  strength  or  more,  then  at  least  a 
2  per  cent,  solution  should  be  added,  volume  for  volume, 
to  the  matter  to  be  disinfected,  and  should  be  thoroughly 
mixed  with  the  latter  in  order  that  the  germicide  may  be 
brought  into,  contact  with  all  the  infective  organisms. 

Chlorinated  Lime. — Chlorinated  lime  (often  called  chlo- 
ride of  lime)  is  one  of  the  best  and  cheapest  disinfectants. 
It  should  contain  at  least  35  per  cent,  of  available  chlorine, 
should  be  kept  covered  from  air  and  moisture,  and  fresh 
solutions  should  always  be  made  as  needed.  Its  power 
is  due  to  hypochlorite  of  lime,  w^hich  is  freely  soluble  in 
matter,  giving  up  chlorine  gas — a  most  powerful  disin- 
water  and  readily  dissociates  in  contact  with  organic 
fectant — and  also  liberating  nascent  ox>'gen  that  in  turn 
acts  powerfully  upon  the  organic  matter  present,  including 
living  microorganisms.  "Germs  of  all  kinds,  including 
the  most  resistant  spores,  are  destroyed  by  this  solution; 
but  it  must  be  remembered  that  the  disinfectant  itself 
is  quickly  decomposed  and  destroyed  by  contact  with 
organic  matter,  and  that  if  this  is  present  in  excess, 
disinfection  may  not  be  accomplished,  especially  w^hen 
the  germs  are  embedded  in  masses  of  material  which 
are  left  unacted  upon  after  the  hypochlorite  of  lime 
has  been  all  exhausted  in  the  solution."  Labarraque's 
solution  of  chlorinated  soda  is  also  an  effective  mild  dis- 
infectant, but  does  not  keep  well,  and  chlorinated  lime  is 


348  DISINFECTION 

equally  good  and  much  cheaper.  However,  the  soda 
solution  has  scarcely  any  disagreeable  odor,  and  makes  a 
pleasant  disinfecting  bath  for  the  person.  The  official 
solution  must  contain  at  least  3  per  cent,  of  available 
chlorine,  but  it  may  be  diluted  with  from  two  to  five 
parts  of  water  before  use,  especially  for  bathing. 

''Though  probably  effective  against  sporeless  bacteria  in 
somewhat  less  proportions,  solutions  of  chlorinated  lime 
should  be  of  at  least  1  per  cent,  strength  by  weight,  and 
should  be  used  in  excess,  to  allow  for  both  the  dilution  by 
the  mass  to  be  disinfected  and  the  exhaustion  of  the 
hypochlorite  by  organic  matter.  "In  the  U.  S.  Army 
a  4  per  cent,  strength  of  chlorinated  lime  in  solution  is 
officially  prescribed  for  use  in  disinfection  of  the  excreta 
of  the  sick,  it  being  specifically  stated  that  the  chlorinated 
lime  so  used  shall  be  of  good  quality  and  not  have  under- 
gone decomposition.''^ 

Bichloride  of  Mercury. — Bichloride  of  mercury  (corrosive 
sublimate)  is  one  of  the  best  germicides  that  we  have,  and 
is  effective  in  comparatively  weak  solutions.  It  corrodes 
metal,  and  so  cannot  be  used  to  disinfect  waste-pipes,  etc.; 
and  it  combines  with  and  coagulates  albumin,  which  inter- 
feres somewhat  with  its  action.  This  coagulation  is  pre- 
vented to  a  degree  by  the  addition  of  a  small  amount 
of  citric  or  tartaric  acid  to  the  solution,  which  addition 
also  favors  the  solution  and,  as  was  first  shown  by 
Laplace,  increases  the  efficiency  of  the  mercurial  salt. 
The  same  result  is  said  to  be  obtained  if  one  part  of 
hydrogen  peroxide  (15  per  cent,  solution),  be  added  to 
three  parts  of  a  corrosive  sublimate  solution  of  any 
strength.  Common  salt  (0.5  to  1  per  cent.)  or  ammonium 
chloride  when  added  to  twice  the  quantity  of  corrosive 
sublimates  increase  its  solubility,  but  they  are  said  to 
diminish  its  efficiency  somewhat.  However,  it  is  better  not 
to  use  corrosive  sublimate  in  disinfecting  fecal  excreta  or 
sputum,  as  these  always  contain  more  or  less  albumin,  and 

1  Rosenau's  Preventive  Medicine  and  Hygiene,  p.  1019. 


CHEMICAL  DISINFECTANTS  349 

also  because  the  sulphur  present  in  the  excreta  permits  the 
formation  of  a  sulphide  of  mercury,  which  has  almost  no 
power  as  a  disinfectant.  A  lime  solution  is  better  and 
more  certain. 

Bichloride  of  mercury  should  be  used  in  solutions  of 
from  1  in  1000  to  1  in  500  strength  for  ordinary  disin- 
fection, though  weaker  preparations  are  sometimes  used 
in  surgical  cases.  It  is  especially  valuable  where  a  large 
amount  of  fluid  is  to  be  freely  used,  but  on  account  of  its 
poisonous  properties  and  the  consequent  danger  of  accident 
from  a  lack  of  color,  stock  solutions  should  always  be  colored 
by  adding  a  little  aniline  dye  or  copper  sulphate.  Ab- 
bott cautions  that  the  stains  of  blood  and  feces  on  cloth- 
ing are  rendered  almost  indelible  by  long  soaking  in 
bichloride  solutions.  Silver  nitrate  is  almost,  if  not  fully, 
as  good  a  disinfectant  as  bichloride  of  mercury,  and 
does  not  coagulate  albumin  so  readily,  but  is  much  more 
expensive  and  has  the  objectionable  property  of  perman- 
ently staining  many  things. 

Carbolic  Acid. — Carbolic  acid  is  effective  in  the  absence 
of  spores,  and,  according  to  Koch,  should  have  first 
place  in  disinfection  against  the  cholera  germ.  It  is  of 
doubtful  value,  however,  in  cases  of  typhoid  fever,  as 
it  is  said  that  the  typhoid  bacilli  can  be  cultivated  in  a 
medium  containing  0.5  per  cent,  of  carbolic  acid;  nor 
is  it  reliably  efficient  against  spore-forming  organisms. 

Solutions  should  always  be  made  by  first  dissolving  the 
acid  in  hot  water,  and  should  contain  from  2  to  5  per  cent, 
of  acid,  the  latter  being  practically  a  saturated  solution. 
The  addition  of  a  small  quantity  of  glycerin  is  said  to 
facilitate  the  solution.  The  stronger  solution  is  especially 
valuable  for  the  direct  disinfection  of  human  excreta 
of  all  kinds,  but  must  be  thoroughly  mixed  with  the  same, 
as  carbolic  acid  coagulates  albumin,  though  not  to  the 
degree  caused  by  bichloride  of  mercury;  while  the  weaker 
fluid  (2  or  3  per  cent.)  may  be  used  freely  for  the  disin- 
fection of  clothing  or  the  washing  of  walls,  floors,  furniture, 
etc.     A  2  or  3  per  cent,  solution  of  a  mixture  of  equal 


350  DISINFECTION 

parts  of  carbolic  and  sulphuric  acids  is  valuable  for  the 
disinfection  of  water-closets,  urinals,  etc.,  as  the  latter 
acid  increases  the  effectiveness  of  the  mixture;  but  it 
must  not  be  kept  too  long  in  contact  with  metals  on 
account  of  the  corrosive  action  of  the  sulphuric  acid. 
Rosenau  states  that  the  addition  of  0.5  per  cent,  of 
hydrochloric  acid  to  carbolic  acid  aids  its  activity. 

Solutions  of  the  cresols  (meta-,  para-,  and  ortho-),  which 
are  derived  from  coal-  or  wood-tar,  and  much  resemble 
carbolic  acid,  may  be  used  for  the  same  purposes  and  in 
about  the  same  strength  as  solutions  of  the  latter.  In  fact, 
tricresol,  which  is  a  refined  combination  of  the  three,  is  two 
or  three  times  as  powerful  a  disinfectant  as  carbolic  acid, 
and,  in  solutions  of  from  0.5  to  1  per  cent,  strength,  makes 
an  agreeable  and  efficient  disinfectant  for  use  in  surgery 
and  obstetrics,  especially  as  it  does  not  coagulate  albumin 
as  readily  as  do  carbolic  acid  and  corrosive  sublimate.  As 
carbolic  acid  and  cresol  solutions  are  all  poisonous,  they 
should  always  be  so  labelled,  although  the  characteristic 
odor  serves  as  a  partial  safeguard  to  those  accustomed 
to  it. 

The  cresols  do  not  corrode  metals  and  can  be  used  with 
soaps  and  oils  to  form  emulsions,  both  of  which  features 
increase  their  usefulness  for  surgical  and  other  purposes. 

Creolin. — Creolin  is  another  coal-tar  product  that  has 
some  germicidal  power,  but  is  not  so  efficient  as  was 
formerly  credited.  Being  cheap,  it  may  be  used  freely 
for  disinfecting  drains,  stables,  urinals,  and  such  places 
where  its  rather  strong  odor  is  not  objectionable.  It  should 
be  made  up  in  from  2  to  5  per  cent,  strength  in  water, 
and,  being  insoluble,  the  mixture  must  be  thoroughly 
stirred  or  shaken  each  "time  before  use! 

As  McClintock  and  Frey  have  shown  that  most  of  the 
coal-tar  disinfectants,  including  carbolic  acid  and  the 
cresols,  do  not  destroy  the  virulence  of  vaccine  virus 
in  the  strength  and  time  in  which  they  kill  practically 
all  non-spore-forming  bacteria,  "the  inference  is  allow- 
able that  this  class  of  disinfectants  is  not  safe  to  use  for 


CHEMICAL  DISINFECTANTS  351 

such  diseases  as  smallpox  and  the  presumably  protozoal 
diseases,  such  as  syphilis,  measles,  scarlet  fever,  etc."^ 

Zinc  Chloride. — Zinc  chloride  is  a  good  antiseptic  and 
deodorant,  but  not  a  very  powerful  disinfectant.  A  5  to 
10  per  cent,  solution  will  kill  germs  without  spores. 

Calcium  Hydrate. — Calcium  hydrate,  when  mixed  with 
water  to  make  a  thin  whitewash  (milk  of  lime),  is  said  to 
be  a  good  disinfectant,  especially  for  excreta,  etc.,  and  is 
one  of  the  cheapest  and  easiest  to  obtain.  It  should  be 
added  to  the  infectious  matter  in  excess  or  until  the 
mixture  is  decidedly  alkaline  and  will  require  from  one 
to  two  hours  to  disinfect  thoroughly. 

The  proportion  of  lime  to  water  should  be  about  as  1  to 
4,  equal  parts  being  first  taken  to  allow  the  slaking  of  the 
lime,  and  the  rest  of  the  water  then  added  and  the  mass 
thoroughly  mixed  by  stirring.  Two  quarts  of  this  mixture 
per  day  for  each  person  using  a  cesspool  will  keep  the 
contents  of  the  latter  disinfected  and  free  from  putre- 
factive odors,  provided  its  use  commences  with  the  use  of 
the  cesspool,  or  that  the  prior  contents  have  been  dis- 
infected by  an  excess  of  this  or  a  chlorinated  lime  solu- 
tion, or  by  an  abundance  of  the  latter  salt  or  quicklime  in 
powder.  Air-slaked  lime  should  not  be  used  to  make  up 
the  "milk  of  lime,"  as  it  is  practically  worthless,  but  the 
lime  should  always  be  freshly  slaked  with  water  as  indi- 
cated or  else  kept  in  an  air-tight  container  after  such 
slaking. 

Sulphate  of  Iron. — Sulphate  of  iron,  which  acts  as  an 
antiseptic  to  prevent  putrefaction,  rather  than  as  a 
disinfectant,  may  also  be  added  to  the  contents  of  an 
offensive  cesspool  or  one  that  has  received  infected  matter 
to  the  extent  of  about  four  pounds  for  each  cubic  yard 
of  the  mass.  The  sulphate  should,  of  course,  be  thoroughly 
dissolved  before  using. 

Hydrogen  Peroxide  or  Dioxide. — An  extremely  valuable 
disinfectant  for  local  or  topical  applications  to  the  person 

*  Rosenau.  loc.  cit,  p.  1012. 


352  DISINFECTION 

is  hydrogen  peroxide  or  dioxide  (H2O2).  It  is  harmless, 
even  when  taken  internally;  is  effective  in  comparatively 
weak  solutions,  and  is  especially  active  in  the  destruction 
of  pus  organisms.  It  is  usually  supplied  in  the  form  of  a 
15  per  cent,  solution  in  water  and  at  present  only  its 
high  cost  prevents  its  more  extended  use. 

Chlorine  and  Sulphur  Dioxide. — Until  the  discovery, 
in  1892,  of  the  great  disinfecting  power  of  formaldehyde 
or  formic  aldehyde  by  Trillat  and  Aronson,  about  the 
only  gaseous  disinfectants  of  practical  value  were  chlorine 
and  sulphur  dioxide. 

Of  these,  chlorine  is  the  more  powerful  and  efficient, 
but  the  distressing  and  oftentimes  serious  symptoms  which 
it  produces  when  accidentally  inhaled,  and  the  bleaching 
effect  that  it  has  upon  many  articles,  have  both  tended  to 
prevent  its  common  employment.  Like  the  sulphur 
dioxide,  it  acts  best  in  the  presence  of  moisture,  and 
therefore  steam  should  be  simultaneously  introduced  and 
liberated  in  the  room  or  enclosure  in  which  either  of  these 
disinfectants  is  used.  Sufficient  chlorine  for  1000  cubic 
feet  of  space  may  be  generated  by  carefully  pouring  two 
fluidounces  of  strong  sulphuric  acid  and  three  fluidounces 
of  water,  previously  mixed  and  cooled,  upon  eight  ounces 
of  sodium  chloride  (common  salt)  and  two  ounces  of  man- 
ganese dioxide.  The  acid  must  be  added  to  the  water 
little  by  little  and  with  care,  and  the  salt  and  manganese 
should  be  in  an  earthen  vessel  upon  a  bed  of  sand,  to 
prevent  injury  to  the  floor  or  carpet.  Moreover,  as  the 
chlorine  gas  is  very  heavy,  the  generating  apparatus 
should  be  at  as  high  a  level  as  possible  in  the  room  to  get 
even  fair  diffusion. 

Sulphur  dioxide  (SO2),  though  not  so  positive  in  its  ac- 
tion as  chlorine,  is  more  frequently  employed  on  account 
of  the  lesser  risk  and  trouble  connected  with  it.  It  prob- 
ably kills  germs  not  containing  spores  if  sufficiently  con- 
centrated and  in  the  presence  of  moisture,  and  is  therefore 
useful  in  the  fumigation  of  rooms  and  of  articles  that 
cannot  be   subjected  to   steam-heat   or    chemical   solu- 


CHEMICAL  DISINFECTANTS  353 

tions.  But  it  will  bleach  or  tarnish  many  articles,  and 
for  this  reason  and  the  fact  that  it  is  thought  by  some  to 
be  inferior  to  formaldehyde,  its  use  has  been  in  a  measure 
supplanted  by  that  of  the  latter  whenever  that  could  be 
obtained. 

To  secure  sufficient  concentration  at  least  three  pounds 
of  sulphur  should  be  burned  for  every  1000  cubic  feet  of 
air-space. 

The  sulphur  should  be  well  moistened  with  alcohol, 
unless  the  prepared  sulphur  candles  now  on  the  market 
are  used,  and  allowance  should  be  made  for  a  considerable 
proportion  that  is  usually  not  burned.  Care  must  also  be 
had  to  guard  against  setting  fire  to  the  room  from  the 
sputtering  of  the  sulphur,  and  especially  to  have  present 
in  the  atmosphere  an  abundance  of  aqueous  vapor. 

Before  the  fumigation  of  a  room  with  chlorine  or  sul- 
phur dioxide,  or  with  formaldehyde,  all  apertures  and 
crevices  in  the  walls,  ceiling,  or  floor  should  be  carefully 
closed  from  the  outside  to  maintain  the  gases  in  as  con- 
centrated a  state  as  possible  during  the  process,  which 
should  continue  for  at  least  twenty-four  hours  in  the  case 
of  chlorine  or  sulphur  gas,  and  for  not  less  than  twelve 
hours  with  formaldehyde.  After  the  fumigation  the  room 
should  be  thrown  open  and  well  ventilated,  and  then 
thoroughly  cleansed  with  a  corrosive  sublimate,  carbolic 
acid,  or  hot  soda  solution,  a  4  per  cent,  solution  of  the 
latter  being  not  only  cleansing,  but  strongly  disinfectant 
as  well. 

Sulphur  gas  excels  formaldehyde  in  the  destruction  of 
such  vermin  as  roaches,  bed-bugs,  fleas,  flies,  and  mos- 
quitoes, and  may  be  preferred  to  the  latter  or  used  as  an 
adjunct  to  it  where  there  is  danger  of  infection  being 
transmitted  by  these  agents.  Likewise,  it  may  be  used 
to  destroy  larger  animals,  such  as  rats  and  mice,  that 
we  now  know  may  be  carriers  of  various  disease  germs. 
(See  p.  364.) 

Hydrocyanic  acid,  which  may  be  freely  liberated  as  a 
gas  by  the  addition  of  dilute  sulphuric  acid  to  cyanide  of 
23 


354  DISINFECTION 

potassium,  has  been  used  both  as  a  germicide  and  an  in- 
secticide. Its  high  relative  cost  does  not  warrant  its  use 
as  a  substitute  for  sulphur-gas  or  formaldehyde,  but  the 
certainty  with  which  it  kills  all  kinds  of  small  vermin, 
and  even  higher  animals,  such  as  rats  and  mice,  that  may 
carry  infective  organisms,  renders  it  of  high  value  for  this 
purpose.  Its  poisonous  nature,  however,  should  always  be 
remembered,  and  great  care  always  observed  in  its  use. 

Formaldehyde. — Formaldehyde  (formic  aldehyde),  both 
in  its  gaseous  state  and  in  solution,  is  undoubtedly  one 
of  the  best  and  most  efficient  disinfectants  now  in  use. 
It  has  considerable  penetrating  power,  although  less  than 
steam  or  than  was  claimed  for  it  at  first  by  its  more 
enthusiastic  advocates,  while  for  surface  disinfection  it 
acts  almost  immediately.  It  is  much  better  in  this 
respect  than  chlorine  or  sulphur  dioxide,  already  men- 
tioned, and  where  it  is  properly  used,  only  such  articles 
as  bedding,  mattresses  and  pillows,  that  can  be  better 
treated  with  steam,  need  be  removed  from  an  infected 
apartment.  Clothing,  rugs,  hangings,  etc.,  that  can  be 
freely  exposed  to  it  are  quickly  sterilized.  Another 
important  feature  is  that  it  does  not  bleach  nor  act 
destructively  on  either  clothing  or  furniture,  and  that, 
although  it  is  quite  irritating  to  the  conjunctivae  of  the 
eyes  and  to  other  mucous  membranes  when  concentrated, 
it  is  virtually  non-poisonous. 

Formaldehyde  is  readily  absorbed  and  held  in  solution 
by  water  to  the  extent  of  40  per  cent,  by  weight  of  the 
latter,  but  as  soon  as  this  proportion  is  exceeded  there  is 
a  polymerization  of  the  gas  and  a  solid  (paraformalde- 
hyde or  paraform)  is  precipitated,  which  is  only  resolved 
again  into  formaldehyde  at  a  temperature  of  275°  F. 
The  40  per  cent,  solution  is  practically  identical  with  the 
preparation  which  is  commercially  known  as  formalin, 
which  has  usually  an  addition  of  10  per  cent,  of  methyl 
alcohol  as  an  additional  safeguard  against  precipitation. 
Very  weak  solutions  (1  or  2  per  cent.)  of  the  gas  are  still 
effectively  disinfectant,  while  its  virtue  as  an  antiseptic 


CHEMICAL  DISINFECTANTS 


355 


persists  even  when  the  dilution  is  carried  to  a  remarkable 
degree. 

One  peculiar  effect  of  the  solutions  is  that  of  rendering 
connective  tissue  and  all  gelatinous  substances  insoluble 
in  either  hot  or  cold  water,  and  it  is  probably  to  this  that 
its  germicidal  activity  is  largely  due,  since  the  food-supply 
of  the  bacteria,  if  not  the  substance  of  the  latter  them- 
selves, is  partly  of  this  nature.  For  the  same  reason  it 
hardens  and  disagreeably  roughens  the  skin,  which  tend 
to  prevent  its  use  for  topical  applications  to  the  human 
body. 


Fig.  90. — Schering's  lamps  for  volatilizing  paraform. 


Several  methods  have  been  devised  for  the  production 
or  liberation  of  formaldehyde  in  rooms  and  buildings 
in  such  volume  as  positively  to  secure  both  surface  and 
penetrative  disinfection.  One  of  the  first  devised  and 
best  methods  involves  the  heating  and  vaporizing  of  a 
solution  of  gas,  such  as  formalin  or  formochloral,  the 
latter  a  mixture  of  the  former  with  calcium  chloride. 
For  instance,  in  Trillat's  apparatus  the  latter  solution  is 
used,  the  calcium  chloride  being  added  to  insure  against 
the  precipitation  of  paraform.  A  simpler  device,  called 
a  regenerator,  allows  formalin  to  flow  in  a  fine  stream 
through  a  copper  coil  heated  to  redness  by  a  flame  be- 
neath, the  gas  and  vapor  then  passing  directly  into  the 


356 


DISINFECTION 


room  in  a  superheated  and  effective  condition;  and  in 
other  apparatus,  hke  the  Novy-Waite  and  Trenner-Lee 
generators,  there  is  special  provision  for  the  rapid  evolution 
of  the  gas  at  high  temperature  and  to  prevent  its  poly- 
merization. Both  of  these  methods  have  the  advantage 
that  the  apparatus  may  be  operated  outside  of  the  room 
to  be  disinfected,  and  the  action  accordingly  controlled; 


Fig.  91. — Modified  Novy-Waite  formaldehyde  generator. 


also  that  the  amount  of  gas  liberated  depends  directly 
upon  the  strength  and  quantity  of  the  solution  evaporated. 
In  the  Schering  method  the  solid  paraform  is  heated 
in  a  receptable  over  an  alcohol  lamp,  the  volume  of 
resulting  formaldehyde  depending,  of  course,  upon  the 
amount  of  paraform  used.  This  method  has  yielded  some 
excellent  results  experimentally,  and  is  of  special  value 


CHEMICAL  DISINFECTANTS 


357 


in  disinfecting  small  rooms,  closets,  and  sterilizing  cases 
for  instruments,  dressings,  etc. 

The  gas  may  also  be  liberated  in  a  room  by  spraying 
formalin  from  a  properly  constructed  compressed  air  or 
steam  atomizer,  or  by  evaporating  it  from  saturated  sheets 
hung  about  the  room,  but  as  this  is  not  certain  to  liberate 
all  the  gas  from  the  solution,  more  of  the  latter  must 
be  used. 


FiQ.  92. — The  Trenner-Lee  formaldehyde  generator. 

Formerly  a  very  common  form  of  apparatus  was  that 
devised  in  the  form  of  a  portable  lamp  to  develop  the 
gas  directly  by  the  oxidation  of  methyl  alcohol,  the 
vapors  of  the  latter  being  made  to  pass  over  or  through 
tubes  or  coils  of  heated  platinum,  and  to  be  thus  converted 
into  the  disinfectant  gas.    Considerable  formaldehyde  can 


358  DISINFECTION 

doubtless  be  produced  in  this  way,  but  with  most  ap- 
paratus of  this  kind  the  amount  at  any  time  is  uncertain 
and  the  results  indefinite,  since  part  of  the  alcohol  vapors 
are  polymerized  and  part  are  further  oxidized  into  com- 
pounds such  as  carbon  monoxide  and  carbon  dioxide. 
Therefore,  with  such  apparatus,  this  method  is,  as  a  rule, 
only  to  be  advised  for  comparatively  small  apartments 
or  enclosures,  and  not  where  certainty  of  disinfection  is 
important.  However,  these  objections  have  been  over- 
come in  the  Kuhn  generator,  which  is  simple  and  positive 
in  operation  and  manipulation,  and  has  been  proved 
efficient  and  reliable  under  severe  tests. 

Abbott  states  that  he  has  "obtained  the  most  satis- 
factory results  through  the  use  of  formalin  to  which  10 
per  cent,  of  glycerin  has  been  added,  as  recommended  by 
Schlossmann;  and  through  the  employment  of  a  generator 
after  the  plan  of  that  advised  by  Novy  and  Waite.  In 
these  tests  we  found  that  80  per  cent,  of  all  exposed 
infected  objects  in  a  room  could  be  disinfected  when 
500  c.c.  of  the  formalin-glycerin  mixture  per  1000  cubic 
feet  of  air-space  was  completely  evaporated  and  the  room 
kept  closed  for  three  or  four  hours. "^ 

In  the  other  apparatus  one  pound  of  formalin  or 
fprmochloral,  from  50  to  75  of  Schering's  paraform 
tablets,  or  a  quart  of  methly  alcohol  are  to  be  respectively 
used  for  each  1000  cubic  iept  of  air-space  to  be  disinfected.^ 

A  very  simple  method  of  liberating  formaldehyde-gas 
and  one  whose  efficacy,  it  is  asserted,  has  been  thoroughly 
established  by  laboratory  tests,  is  to  pour  one  pound  of 
formalin  containing  40  per  cent,  of  formaldehyde  on  eight 
ounces  of  permanganate  of  potash  in  a  high  vessel,  this 
being  the  proper  amount  for  1000  cubic  feet  of  space  or 
less.  The  gas  is  liberated  freely  and  speedily,  and  with 
but  little  risk  of  polymerization  or  of  any  remaining  in 
solution.      Of  course  the  effectiveness  of  action  will  be 


1  Hygiene  of  Transmissible  Diseases,  1899,  p.  269. 

2  See  also  U.  S.  Quarantine  Regulations,  as  quoted  on  p.  361. 


CHEMICAL  DISINFECTANTS 


359 


enhanced  by  the  previous  or  coincident  vaporizing  of 
water  in  the  room. 

Whenever  formaldehyde  is  employed  as  a  gas,  all  the 
apertures  in  the  room  should  be  carefully  and  tightly 
closed,  since,  having  the  same  specific  gravity  as  the  air, 
its  diffusion  takes  place  rapidly.  Moreover,  after  a 
sufficient  volume  of  the  gas  has  been  liberated,  it  should 
be  allowed  to  act  as  long  as  possible,  preferably  for  twelve 
hours  at  least,  and  better  for  twenty-four,  since,  though  it 
is  more  rapid,  the  time  element  is  just  as  important  a 
factor  with  this  as  with  other  gaseous  disinfectants.  Fliigge 
thinks  we  obtain  good  results  if  90  per  cent,  of  the  disease 
germs  present  are  killed  by  the  formaldehyde  fumigation. 
Lastly,  the  gas  is  an  excellent  deodorant,  combining  as 
it  does  with  the  effluvia  from  decomposing  substances  to 
produce  odorless  compounds.  Its  odor,  in  turn,  may  be 
quickly  dissipated  from  a  room  by  evaporating  a  little 
ammonia  therein. 

The  following  table  of  Koch  and  Jaeger  is  added  to 
show  the  comparative  disinfectant  strength  of  some 
substances  occasionally  used  for  the  purpose: 


Disinfectant. 

Strength. 

Bichloride  of           f 

1  to  20,000 

mercury     . 

1  to 

1,000 

1  to  12,000 

Silver  nitrate 

1  to 

4,000 

1  to 

2,500 

Acid,  hydrochloric 

2to 

100 

Acid,  sulphuric    .   < 

2  to 
15  to 

100 
100 

Ferrum  chlorate 

5to 

100 

Calcium  chloride 

5to 

100 

Potas.  perman.  . 

.   5  to 

100 

caustic  Ii„>e{°:°^«- 

100 
100 

3t^ 

1,000 

Acid,  carbolic 

^  10  to 

100 

1  to 

100 

Formaldehyde     . 

3  to 

100 

(K.  Walter.) 

Objects  submitted  to 
experiments. 

Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Cholera  and  typhoid 
Diphtheria 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Anthrax  spores 
Cholera 
Typhoid 
Staphylococcus   and 

Streptococcus  pyog 
Anthrax  spores 
Nearly  all  patho- 
genic germs 
Anthrax  spores 
All  other  pathogenic  \ 

germs  / 


Time  required  for 
destruction. 


10  minutes. 

1  minute. 
70  hours. 

2  hours. 
2  hours. 

10  days. 
53  days. 

8  days. 

6  days. 

5  days. 
1  day. 

6  hours. 
6  hours. 
8-11    sec- 
onds. 

24  hours. 
Less  than 
30  minutes. 
15  minutes. 

1  minute. 


360  DISINFECTION 

In  any  case  of  infectious  disease  special  attention  should 
be  given  to  disinfecting  the  excretions  and  secretions 
which  are  known  to  be  most  likely  to  contain  the  disease 
germs,  viz.,  the  desquamating  epithelium  and  likewise  the 
renal  secretion  in  measles,  scarlet  fever,  and  all  the  exan- 
themata; the  dejecta  and  urine  in  typhoid  fever,  cholera, 
tropical  or  infectious  dysentery,  and  in  tuberculosis  of 
the  intestinal  or  genito-urinary  tract;  the  sputum  in 
tuberculosis  of  the  lungs  and  air-passages,  and  in  in- 
fluenza, pneumonia,  and  diphtheria;  secretions  from  the 
throat  and  nose  in  diphtheria,  scarlet  fever,  measles, 
infantile  paralysis  and  cerebrospinal  meningitis;  discharges 
from  abscesses,  suppurating  or  gangrenous  wounds,  etc. 

During  the  course  of  the  illness  there  should  be  no 
more  communication  than  is  absolutely  necessary  between 
the  occupants  of  the  sick-room  and  those  in  the  rest  of 
the  house,  and  a  sheet  should  be  hung  at  the  door  and 
kept  moist  with  some  disinfecting  solution,  as  this  will 
largely  prevent  the  escape  of  infective  dust  particles 
through  the  doorway.  All  articles  going  from  the  room, 
whether  dishes,  clothing,  or  food,  should  be  submerged  in 
a  disinfectant  or  covered  with  a  cloth  wet  with  it,  and 
should  be  burned,  boiled,  or  otherwise  disinfected  as  soon 
as  possible  thereafter.  Excreta  should  be  disinfected  as 
soon  as  discharged  from  the  body,  but  should  not  be 
emptied  into  a  water-closet,  sewer,  or  cesspool  till  the  dis- 
infectant has  had  ample  time  to  do  its  work,  at  least  one 
hour  being  given  for  this  action.  Ventilation  should  be 
as  perfect  as  possible;  sunlight  should  be  admitted  when- 
ever it  will  not  injure  or  annoy  the  patient,  and,  above 
all,  cleanliness  in  every  respect  should  be  insisted  upon  as 
being  most  essential.  Sick-rooms  should  be  well  screened 
to  prevent  the  access  of  flies,  as  these  may  carry  infection 
to  others  from  sputum,  excreta  or  even  the  body  of  the 
patient. 

The  dress  of  the  nurse  or  attendant  should  be  such 
that  dust  and  germs  do  not  readily  adhere  to  it  and  that 
it  may  readily  be  disinfected  and  cleaned,  the  cotton  uni- 


CHEMICAL  DISINFECTANTS  361 

forms  of  a  hospital  training  school  being  almost  ideal  in 
this  respect.  If  this  were  in  the  form  of  an  overgarment 
that  could  readily  be  slipped  off  when  the  nurse  has  to 
leave  the  sick-room,  there  would  be  an  additional  element 
of  safety,  just  as  there  will  be  if  there  is  provided  some- 
thing like  the  long,  old-fashioned  linen  "duster"  for  the 
casual  visitor,  whether  physician  or  parent,  to  slip  on 
when  entering  the  room.  The  nurse  should,  of  course, 
bathe  not  only  the  patient  but  herself  as  well  with  disin- 
fectant solutions,  such  as  Labarraque's  (diluted),  carbolic 
acid,  or  tricresol;  should  destroy  at  once  all  possible  infec- 
tion coming  from  the  patient,  and  at  least  every  other  day 
should  wipe  with  a  cloth  dampened  in  a  disinfectant  all 
window-sills,  tables,  and  other  surfaces  upon  which  dust 
and  the  attached  germs  continually  settle.  A  closet 
with  a  close-fitting  door  may  be  made  to  serve  as  a 
good  disinfecting  chamber  for  garments  that  are  not  in 
immediate  use,  as  a  few  ounces  of  formalin  sprinkled  on 
the  garments  themselves  or  a  few  paraform  tablets  burned 
in  one  of  the  Schering  lamps  will  quickly  sterilize  the 
contents  of  the  closet  without  serious  discomfort  to  the 
occupants  of  the  adjoining  room. 

It  is  taken  for  granted  that,  if  possible,  before  the  occu- 
pancy of  the  room  by  the  sick,  all  upholstered  furniture, 
heavy  drapery  and  everything  not  absolutely  necessary 
were  removed  from  the  room.  Even  the  carpet  should 
be  taken  up  and  rugs  used  temporarily  in  its  place.  If 
this  is  done,  the  work  of  disinfecting  the  room  after  it 
is  no  longer  needed  by  the  patient  will  be  greatly  facilitated. 

Since  Chapin  and  others  have  shown  the  great  pre- 
ponderance of  infections  by  contact,  or  through  intimate 
personal  relationships,  final  disinfection  after  a  case  of 
illness  may  be  deemed  of  less  importance  than  it  was 
formerly  considered  to  be.  Nevertheless,  it  should  be 
looked  upon  as  an  additional  factor  in  preventing  the 
further  spread  of  infection,  and  should  be  carried  through 
with  the  same  thoroughness  that  should  be  observed  in 
other  methods  of  disinfection. 


362  DISINFECTION 

Where  the  use  of  formaldehyde  is  not  available,  the 
final  disinfection  should  be  carried  out  as  follows:  All 
bed-clothing,  etc.,  should  be  either  submerged  in  some 
disinfectant  solution  or  in  boiling  water,  or  else  covered 
with  a  sheet  wet  with  a  disinfectant,  and  boiled  as  soon 
as  possible  thereafter.  No  clothing  should  be  sent  away 
from  the  house  to  be  laundered.  Bed-quilts,  blankets, 
mattresses,  etc.,  should  be  subjected  to  steam  sterilization 
if  possible;  if  not,  the  blankets  and  quilts  should  be 
carefully  sterilized  by  boiling,  and  the  mattresses  had 
better  be  burned,  though  they  may  be  disinfected  inter- 
nally by  the  introduction  of  formalin  or  formaldehyde  gas, 
and  externally  by  wiping  and  wetting  with  a  strong  solu- 
tion of  corrosive  sublimate.  The  carpet  or  rugs  should  be 
carefully  taken  up,  carried  to  an  open  space,  well  beaten, 
and  then  hung  in  the  open  air  for  a  time,  provided  they 
cannot  be  sent  at  once  to  some  place  where  steam  steriliza- 
tion is  available.  All  furniture  and  the  woodwork  of  the 
room  should  be  washed  with  corrosive  sublimate  solution 
(1  to  1000  or  500),  taking  care  to  get  the  fluid  into  all 
crevices.  The  floor  may  be  scrubbed  with  lye  or  hot  soda 
solution  (4  per  cent.),  and  then  mopped  and  flooded  with 
the  corrosive  sublimate  solution.  The  walls  should  also 
be  wiped  with  cloths  wrung  out  of  this  solution,  and  any 
paper  upon  them  removed  after  fumigation,  unless  it  be 
new  and  free  from  cracks.  Or  the  walls  may  be  rubbed 
down  with  crumbs  of  bread  and  the  latter  burned,  as  the 
bread  contains  much  gluten  to  which  the  dust  and  bacteria 
adhere.  Fumigation  with  sulphur  dioxide  is  usually  of 
somewhat  doubtful  efficiency  unless  considerable  attention 
is  given  to  the  details.  If  it  is  employed,  it  should  be  done 
first,  before  the  bedding,  etc.,  is  removed  and  the  walls, 
floors,  and  woodwork  are  wiped  or  washed,  and  all  open- 
ings from  the  room,  cracks,  crevices,  etc.,  should  be  closed 
by  sealing  on  the  outside,  and  sufficient  gas  liberated  by 
suitable  means.  The  vessels  containing  the  gas-generating 
substances  should  be  placed  in  larger  vessels  containing 
water  to  avoid  the  danger  of  fire,  and  vapor  of  water 


PHYSICAL  DISINFECTANTS  363 

should  be  liberated  in  some  way  simultaneously  with  the 
gas,  say  by  placing  hot  bricks  or  the  like  in  the  water, 
or  else  water  should  be  sprayed  freely  from  an  atomizer 
over  everything  in  the  room,  as  sulphurous  acid  has  little 
disinfecting  value  except  in  the  presence  of  moisture, 
which  also  greatly  enhances  the  effects  of  formaldehyde. 
The  room  should  then  remain  closed  for  twenty-four 
hours,  and,  lastly,  should  be  well  ventilated  for  a  day 
or  two  before  being  furnished  and  occupied  again. 

Should  it  be  possible  to  use  formaldehyde,  the  disinfec- 
tion is  much  simplified,  and  is  to  be  carried  out  in  the 
way  already  indicated;  but  whatever  the  gaseous  disin- 
fectant employed,  it  should  always  be  followed  by  the 
washing  or  wiping  of  walls,  ceilings,  floor,  and  all  exposed 
surfaces  with  a  disinfectant  solution,  and  by  the  steam 
sterilization  or  boiling  of  all  removable  articles  where- 
ever  possible.  In  fact,  it  should  be  remembered  that 
no  one  of  these  processes  will  in  any  probability  destroy 
all  the  infection,  but  that  each  must  be  carried  out  with 
conscientious  thoroughness  and  strictest  attention  to  detail 
in  order  to  secure  the  greatest  measure  of  success. 

Where  flies,  mosquitoes  or  other  germ-carrying  vermin 
are  possibly  present,  it  may  be  advisable  to  follow  the 
fumigation  by  formaldehyde  with  another  by  sulphur 
dioxide,  as  the  latter  is  much  the  more  certain  to  kill 
both  insects  and  rodents.  The  gas  from  1  pound  of 
burning  sulphur  per  1000  cubic  feet  of  space  should  kill 
flies  and  mosquitoes  within  two  hours ;  that  from  2  pounds 
should  kill  rats  within  four  hours,  and  that  from  5  pounds 
should  kill  bed-bugs,  lice,  etc.,  within  six  hours. 

The  United  States  Quarantine  Regulations,  promul- 
gated October  20,  1910,  authorize  the  following  disin- 
fectants and  the  methods  of  generating  and  using  them: 

PHYSICAL  DISINFECTANTS. 

Burning. — Of  unquestioned  efficiency,  but  seldom  re- 
quired. 


364  DISINFECTION 

Boiling. — Very  efficient  and  of  wide  range  of  applica- 
bility. The  articles  must  be  wholly  immersed  for  not  less 
than  thirty  minutes  in  water  actually  boiling  (100°  C). 
The  addition  of  1  per  cent,  of  carbonate  of  soda  renders 
the  process  applicable  to  polished  steel,  cutting  instru- 
ments or  tools. 

Steam. — (a)  Flowing  steam  {not  under  pressure). 
Flowing  steam  (not  under  pressure)  when  applied  under 
suitable  conditions  is  an  efficient  disinfecting  agent.  The 
exposure  must  be  continued  thirty  minutes  after  the  tem- 
perature has  reached  100°  C. 

{h)  Steam  under  pressure  without  vacuum.  Steam 
under  pressure  will  sterilize,  provided  that  the  process  is 
continued  twenty  minutes  after  the  pressure  reaches  15 
pounds  per  square  inch.  The  air  must  be  expelled  from 
the  apparatus  at  the  beginning  of  the  process.  If  im- 
practicable to  obtain  the  designated  pressure,  a  longer 
exposure  will  accomplish  the  same  result. 

(c)  Steam  under  pressure  with  vacuum.  Steam  in  a 
special  apparatus  with  vacuum  attachment  is  the  best 
method  of  applying  steam  under  pressure,  the  object  of 
the  vacuum  apparatus  being  to  expel  the  air  and  to  pro- 
mote the  penetration  of  the  steam.  The  process  is  to  be 
continued  for  twenty  minutes  after  the  pressure  reaches 
10  pounds  to  the  square  inch. 


GASEOUS  DISINFECTANTS. 

Sulphur  Dioxide. — Sulphur  dioxide  is  efficient,  but  re- 
quires the  presence  of  moisture.  It  is  only  a  surface 
disinfectant,  and  is  lacking  in  penetrating  properties. 
An  atmosphere  containing  4.5  per  cent,  can  be  obtained 
by  burning  5  pounds  of  sulphur  per  1000  cubic  feet  of 
space.  This  amount  would  require  the  evaporation  or 
volatilization  of  about  one  pint  of  water.  Under  these 
conditions  the  time  of  exposure  should  not  be  less  than 
twenty-four  hours   for   bacterial   infections.     A   shorter 


GASEOUS  DISINFECTANTS  365 

time  will  suffice  for  fumigation  necessary  to  kill  mosquitoes 
and  other  vermin. 

The  sulphur  may  be  burned  in  shallow  iron  ovens 
(Dutch  ovens)  containing  not  more  than  30  pounds  of 
sulphur  for  each  pot,  and  the  pots  should  stand  in  vessels 
of  water.  Quicker  and  better  results  can  be  obtained  from 
burning  the  same  total  amount  of  sulphur  in  a  number  of 
small,  shallow  ovens  (Dutch  ovens),  5  to  10  pounds  in 
each,  than  in  a  few  large  ovens.  The  sulphur  ovens 
should  be  elevated  from  the  bottom  of  the  compartment 
to  be  disinfected  in  order  to  obtain  the  maximum  possible 
percentage  of  combustion  of  sulphur.  The  sulphur 
should  be  in  a  state  of  fine  division,  and  ignition  is  best 
accomplished  by  alcohol;  special  care  to  be  taken  with 
this  method  to  prevent  damage  to  cargo  of  vessel  by  fire; 
or  the  sulphur  may  be  burned  in  a  special  furnace,  the 
sulphur  dioxide  being  distributed  by  a  power  fan.  This 
method  is  peculiarly  applicable  to  cargo  vessels. 

Liquefied  sulphur  dioxide  is  now  commercially  available 
and  may  be  used  for  disinfection  in  place  of  sulphur 
dioxide  generated  as  above,  it  being  borne  in  mind  that 
this  process  will  require  two  pounds  of  the  liquefied  gas 
for  each  pound  of  sulphur  as  indicated  in  the  above 
paragraphs. 

Sulphur  dioxide  is  especially  applicable  to  the  holds  of 
vessels,  or  to  freight  cars  and  apartments  that  may  be 
tightly  closed  and  which  do  not  contain  objects  injured  by 
the  gas.  Sulphur  dioxide  bleaches  fabrics  or  materials 
dyed  with  vegetable  or  aniline  dyes.  It  destroys  linen 
or  cotton  goods  by  rotting  the  fiber  through  the  agency 
of  the  acids  formed.  It  injures  most  metals.  It  is 
promptly  destructive  to  all  forms  of  animal  life.  This 
property  renders  it  a  valuable  agent  for  the  extermination 
of  rats,  insects,  and  other  vermin. 

Formaldehyde-gas. — Formaldehyde-gas  is  effective  if 
applied  by  one  of  the  methods  given  below.  Formal- 
dehyde-gas has  the  advantage  as  a  disinfectant  that  it 
does  not  injure  fabrics  or  most  colors.    It  is  not  poisonous 


366  DISINFECTION 

to  the  higher  forms  of  animal  Hfe.  It  fails  to  kill  vermin 
such  as  rats,  mice,  roaches,  bed-bugs,  etc.  The  method  is 
not  applicable  to  the  holds  of  large  vessels.  Formal- 
dehyde is  applicable  to  the  disinfection  of  rooms,  cloth- 
ing, and  fabrics,  but  should  not  be  depended  upon  for 
bedding,  upholstered  furniture,  and  the  like,  when  deep 
penetration  is  required.^ 

Many  formaldehyde  solutions  do  not  contain  40  per 
cent,  of  formaldehyde,  and  all  are  apt  to  deteriorate  with 
time.  It  is  therefore  necessary  to  use  a  quantity  in  excess 
of  the  amount  prescribed  in  these  regulations,  unless  the 
solution  has  been  recently  analyzed. 

The  following  methods  of  evolving  the  gas  may  be  used : 

(a)  Autoclave  under  pressure,  3  to  12  hours'  exposure. 

(6)  Lamp  or  generator,  6  to  18  hours'  exposure. 

(c)  Spraying,  12  to  24  hours'  exposure. 

{d)  Formaldehyde  and  dry  heat  in  partial  vacuum,  1 
hour's  exposure. 

{e)  Chemical,  as  formalin-permanganate  method  of 
Russel,  or  formalin-aluminum  sulphate-lime  method  of 
Walker,  6  to  18  hours'  exposure. 

The  minimum  number  of  hours'  exposure,  as  given 
above,  applies  to  empty  rooms  of  tight  construction 
containing  smooth,  hard  surfaces;  the  maximum  number 
of  hours'  exposure  applying  in  all  cases  to  textiles  and 
other  articles  of  a  similar  kind  requiring  more  or  less 
penetration. 

Autoclave  under  pressure:  This  method  has  consider- 
able penetrating  power  when  applied  as  detailed  below. 
Rooms  or  apartments  need  no  special  preparation  beyond 
the  ordinary  closing  of  doors  and  windows.  Pasting, 
caulking,  or  chinking  of  ordinary  cracks  and  crevices  is 
not  necessary.  The  doors  of  lockers  and  closets  and  the 
drawers  of  bureaus  should  be  opened.  In  this  apparatus 
use  formalin  (40  per  cent.),  with  the  addition  of  a  neutral 
salt,  such  as  calcium  chloride  (20  per  cent.).  The  gas 
must  be  evolved  under  a  pressure  not  less  than  45  pounds. 

^  It  should  be  noted  that  formaldehyde  disinfection  is  more  efficient 
in  warm,  moist,  or  still  weather  than  in  cold,  dry,  and  windy  weather. 


GASEOUS  DISINFECTANTS  367 

After  the  gas  is  separated  from  its  watery  solution  the 
pressure  may  be  allowed  to  fall  and  steam  projected  into 
the  compartment  to  supply  the  necessary  moisture.  Use 
not  less  than  10  ounces  of  formalin  per  1000  cubic  feet, 
and  keep  the  room  closed  for  three  to  twelve  hours  after 
the  completion  of  the  process.  For  large  rooms  the  gas 
must  be  introduced  at  several  points  as  far  apart  as  pos- 
sible. It  is  applicable  to  the  disinfection  of  clothing  and 
fabrics  suspended  loosely  in  such  a  manner  that  every 
article  is  freely  accessible  to  the  gas  from  all  directions. 

Lamp  or  generator:  This  method  requires  an  apparatus 
producing  formaldehyde  by  a  partial  oxidation  of  wood 
alcohol,  and  in  using  it  the  room  or  apartment  should  be 
rendered  as  tight  as  practicable.  Oxidize  24  ounces  of 
wood  alcohol  per  1000  cubic  feet,  and  keep  the  room 
closed  from  six  to  eighteen  hours,  in  accordance  with  the 
provisions  in  a  previous  paragraph.  This  method  leaves 
little  or  no  odor.  When  applied  to  clothing  and  textiles, 
the  articles  should  be  suspended  in  a  tight  room  and  so 
disposed  as  to  permit  free  access  of  the  gas.  (See  also 
previous  paragraph.)  The  wood  alcohol  should  be  of  95 
per  cent,  strength,  and  should  not  contain  more  than  5 
per  cent,  of  acetone. 

Spraying:  The  formalin  (40  per  cent.)  should  be 
sprayed  on  sheets  suspended  in  the  room  in  such  a  man- 
ner that  the  solution  remains  in  small  drops  on  the  sheet. 

Spray  not  less  than  10  ounces  of  formalin  (40  per  cent.) 
for  each  1000  cubic  feet.  Used  in  this  way  a  sheet  will 
hold  about  5  ounces  without  dripping  or  the  drops  run- 
ning together.  The  room  must  be  very  tightly  sealed 
in  disinfecting  with  this  process,  and  kept  closed  not  less 
than  twelve  hours.  The  method  is  limited  to  rooms  or 
apartments  not  exceeding  2000  cubic  feet.  The  formalin 
may  also  be  sprayed  upon  the  walls,  floors,  and  objects  in 
the  rooms. 

This  method  is  markedly  interfered  with  by,  and  is  not 
to  be  relied  on  at,  low  temperatures,  say  below  72°"  F. 
At  43.5°  F.,  very  little  formaldehyde  is  liberated,  the 
formaldehyde  being  polymerized  on  the  sheets. 


368  DISINFECTION 

Formaldehyde  with  dry  heat  in  partial  vacuum:  This 
method  has  superior  penetrating  powers  and  is  especially 
applicable  to  clothing  and  baggage.  The  requirements  of 
this  method  are  (1)  dry  heat  of  60°  C.  sustained  for  one 
hour;  (2)  a  vacuum  of  15  inches;  (3)  formaldehyde 
evolved  from  a  mixture  of  formalin  with  a  neutral  salt, 
in  an  autoclave  under  pressure,  using  not  less  than  30 
ounces  of  formalin  (40  per  cent.)  for  1000  cubic  feet;  and 
(4)  a  total  exposure,  under  these  combined  conditions,  of 
one  hour. 

Chemical,  as  (1)  Formalin-permanganate  method. 
When  formalin  is  poured  over  crystals  of  permanganate 
of  potash,  a  vigorous  reaction  takes  place  and  a  large 
quantity  of  formaldehyde-gas  is  liberated.  Reaction  is 
over  in  a  short  time,  five  minutes,  and  if  a  proper  pro- 
portion of  substances  is  used,  the  residue  is  almost  dry. 
The  proportion  is  2  pints  of  formalin  to  1  pound  of  perman- 
ganate of  potash.  One  pint  of  formalin  for  1000  cubic 
feet  of  space  should  be  used  if  the  temperature  is  60°  F. 
or  less;  a  less  amount  may  be  used  for  higher  temperatures, 
but  not  less  than  10  ounces  per  1000  cubic  feet.  This 
method  is  extremely  efficient  on  account  of  the  rapidity 
with  which  the  gas  is  liberated,  but  the  danger  of  fire 
should  be  guarded  against,  as  the  formaldehyde-gas 
being  in  a  comparatively  dry  state,  is  inflammable  in 
the  presence  of  a  light,  such  as  lighted  matches,  lamp,  etc. 

(2)  Formalin-aluminum  sulphate-lime  method.  Add  1 
part  sulphate  of  aluminum  to  2  parts  of  hot  water.  One 
part  of  this  solution  is  added  to  2  parts  of  formalin  (both 
by  volume).  One  part  of  this  second  solution  is  poured 
on  2  parts  of  unslaked  lime  (quick  lime),  broken  into 
small  particles.  The  process  of  liberation  of  formaldehyde- 
gas  is  completed  in  about  twenty  minutes.  This  method 
is  not  as  efficient  as  the  previous  one,  as  less  than  half 
the  amount  of  formaldehyde-gas  is  yielded  from  the  same 
amount  of  formalin. 

Two  pints  of  formalin  per  1000  cubic  feet  of  space  should 
be  used,  if  the  temperature  is  60°  F.  or  less. 


GASEOUS  DISINFECTANTS  369 

Fire  should  be  guarded  against,  but  this  danger  is 
decidedly  less  than  in  the  permanganate  process  on 
account  of  the  large  amount  of  water  vapor  coming 
off  with  the  gas. 

The  stated  times  of  exposure  to  sulphur  dioxide  and 
formaldehyde  are  sufficient  to  destroy  bacterial  infection 
due  to  non-spore-bearing  organisms,  providing  that  the 
infection  is  present  on  the  surface.  If  the  room  is  of 
peculiar,  construction,  so  as  to  impede  the  diffusion  of  the 
gas,  or  if  the  room  is  a  dirty  one,  or  if  on  account  of  any 
other  condition  the  germicidal  action  of  the  gas  is  rendered 
more  difficult,  the  time  of  exposure  should  be  proportion- 
ately increased,  or  supplanted  by  other  methods. 

Chemical  Solutions. — Bichloride  of  Mercury. — Bichloride 
of  mercury  is  a  disinfectant  of  undoubted  potency  and 
wide  range  of  applicability.  It  cannot  be  depended 
upon  to  penetrate  substances  in  the  presence  of  albumin- 
ous matter.  It  should  be  used  in  solutions  of  1  to  1000. 
The  solubility  of  bichloride  of  mercury  may  be  increased 
by  using  sea-water  for  the  solution,  or  by  adding  2  parts 
per  1000  of  sodium  or  ammonium  chloride  to  the  water 
employed. 

Carbolic  Acid. — Carbolic  acid  in  the  strength  of  5  per 
cent,  may  be  substituted  for  the  bichloride  of  mercury,  and 
should  be  employed  in  the  disinfection  of  the  cabins 
and  living  apartments  of  ships  to  obviate  injurious  action 
on  polished  metals,  bright  work,  etc. 

Formalin. — Formalin  containing  40  per  cent,  of  for- 
maldehyde may  be  used  in  a  5  per  cent,  solution  as  a 
substitute  for  bichloride  of  mercury  or  carbolic  acid,  and 
is  useful  for  the  disinfection  of  surfaces,  dejecta,  fabrics, 
and  a  great  variety  of  objects,  owing  to  its  non-injurious 
character. 

In  the  foregoing  chapter  the  author  is  much  indebted  to  A.  C.  Abbott's 
Hygiene  of  Transmissible  Diseases,  and  Rosenau's  Preventive  Medicine 
and  Hygiene  for  authoritative  and  up-to-date  information  as  to  the 
value  of  the  agents  and  methods  of  infection,  and  the  reader  is  referred 
to  these  works  for  an  abundance  of  detail  which  the  limits  of  the  present 
volume  do  not  permit. 
24 


CHAPTER  XL 
QUARANTINE. 

Quarantine  may  be  described  as  the  methods  and 
measures  imposed  by  a  government — local,  State,  or 
national — to  prevent  the  introduction  of  infectious  dis- 
ease into  the  country  or  from  one  locality  to  another. 
Although  the  term  in  itself  is  misleading,  being  derived 
from  the  Italian  quarante  (forty),  and  signifying  the  period 
of  detention  of  the  first  Venetian  quarantines,  it  is  now 
generally  taken  to  indicate  the  entire  routine  of  inspec- 
tion, disinfection,  and  detention,  without  regard  to  the 
length  of  time  involved. 

While  all  civilized  nations  have  from  the  earliest  times 
recognized  the  importance  of  separating  those  afflicted 
with  epidemic  disease  from  the  well,  the  development  of 
the  idea  and  practise  of  quarantine  has  necessarily  been 
consequent  upon  the  growth  of  commerce;  and  while 
there  has  been  isolation  for  leprosy  for  unknown  ages, 
the  first  quarantine  enactments,  in  our  meaning  of  the 
term,  were  put  in  force  in  Venice  about  the  beginning  of 
the  fifteenth  century  as  a  barrier  to  both  the  black  and 
the  Egyptian  plague.  Then  it  was  realized  that  epidemic 
diseases  were  transmitted  by  those  attacked,  a  bureau  of 
health  and  a  lazaretto  were  established,  the  effects  of 
those  who  died  of  the  plague  w^ere  destroyed,  and  the 
period  of  detention  of  incoming  vessels,  passengers,  and 
cargoes  were  fixed  at  forty  days,  the  idea  being  that  this 
period  was  in  itself  more  or  less  mystic  and  salutary. 

As  time  went  on  and  the  plague  spread  over  the  whole 
of  Europe,  the  number  of  lazarettos  was  largely  increased, 
especially  in  the  eighteenth  century.  Of  these,  the  one 
(370) 


HISTORY  AND  PURPOSE  OF  QUARANTINE     371 

at  Marseilles  became  the  most  noted,  not  only  because  it 
was  located  at  one  of  the  most  important  ports  of  the 
Mediterranean,  but  because  of  its  excellent  care  and  man- 
agement. Thanks  to  the  increased  efficacy  of  quarantine 
and  other  sanitary  regulations  as  the  knowledge  concern- 
ing them  developed,  the  plague  rapidly  subsided  soon 
after  the  beginning  of  the  last  century,  and  interest  in 
it  was  supplanted  by  that  in  relation  to  the  frequent  epi- 
demics of  cholera  and  yellow  fever  that  began  to  alarm 
the  civilized  world;  and  it  is  to  prevent  the  ingress  of 
these  latter  diseases,  together  with  leprosy,  smallpox, 
typhus  fever,  and  plague,  that  the  present  quarantine 
regulations  are  in  the  main  devised. 

With  the  knowledge  already  gained  regarding  the 
nature  and  causes  of  infectious  diseases,  their  periods  of 
incubation,  etc.,  it  is  at  once  evident  that  it  will  be  neither 
necessary  nor  wise  to  fix  upon  a  prolonged  and  arbitrary 
time  during  which  vessels  or  passengers  must  be  detained 
in  quarantine.  All  that  is  needed  is  that  the  proper 
inspecting  officers  shall  be  satisfied  that  there  is  no  danger 
of  infection  entering  the  country,  and,  where  any  deten- 
tion is  necessary,  it  is  only  for  so  long  as  will  suffice  for 
the  disinfection  of  the  vessel,  cargo,  and  passengers' 
effects,  and  to  cover  the  period  of  incubation  of  the  sus- 
pected disease. 

The  present  quarantine  laws  of  the  United  States,  and 
the  latest  regulations  of  the  Treasury  Department  based 
upon  them,  are  especially  designed  to  afi'ord  the  greatest 
possible  protection  to  the  country  against  the  importation 
of  disease  with  the  least  possible  detention  of  incoming 
vessels  and  passengers.  An  important  innovation  that 
facilitates  both  these  ends  has  been  the  establishment  of  an 
American  quarantine  in  foreign  lands,  as  it  were,  viz.,  the 
inspection  and,  if  necessary,  detention  and  disinfection  by 
officers  of  this  government  of  all  vessels,  passengers,  and 
cargoes  leaving  a  foreign  port  for  any  port  of  the  United 
States.  This  undoubtedly  greatly  diminishes  the  danger  of 
the  introduction  of  anyjnfectious  disease;  but  in  addition, 


372  QUARANTINE 

there  is  that  section  of  the  law  that  provides  that  the 
President  may,  whenever  the  condition  of  affairs  shall 
seem  to  warrant  it,  "prohibit,  in 'whole  or  in  part,  the 
introduction  of  persons  and  property  from  such  countries 
or  places  as  he  shall  designate  and  for  such  period  of  time 
as  he  shall  deem  necessary." 

Accordingly,  every  vessel  clearing  from  a  foreign  port 
for  this  country  must  obtain  from  the  United  States  con- 
sular officer  of  the  port,  or  from  the  medical  officer  ap- 
pointed for  the  purpose,  a  bill  of  health,  "setting  forth 
the  sanitary  history  and  condition  of  said  vessel,  and  that 
it  has  in  all  respects  complied  with  the  rules  and  regula- 
tions in  such  cases  prescribed  for  securing  the  best  sani- 
tary condition  of  the  said  vessel,  its  cargo,  passengers, 
and  crew."  Before  signing  the  bill  of  health  the  consular 
or  medical  officer  must  be  satisfied  that  the  conditions 
certified  to  therein  are  true,  and  must  inspect  "all  vessels 
from  ports  at  which  cholera,  yellow  fever,  or  plague  in 
men  or  rodents  prevail,  or  at  which  smallpox  or  typhus 
fever  prevails  in  epidemic  form,"  and  "all  vessels  carry- 
ing steerage  passengers."  Moreover  the  vessel  must  be 
clean  in  all  parts,  especially  the  hold,  forecastle  and  steer- 
age, before  stowing  cargo  or  receiving  passengers,  and  all 
parts  liable  to  have  been  infected  by  any  communicable 
disease  must  be  disinfected  before  the  bill  of  health  is  issued. 

"At  ports  where  cholera  prevails  in  epidemic  form, 
special  care  should  be  taken  to  prevent  the  water-  and 
food-supply  from  being  infected.  The  drinking-water, 
unless  of  known  purity,  should  be  boiled  and  the  food 
thoroughly  cooked  and  protected  against  contamination 
by  flies,  etc.  Where  yellow  fever  prevails,  precautions 
should  be  taken  to  prevent  the  introduction  of  mosquitoes 
(stegomyia)  on  board  the  vessel.  At  ports  or  places 
where  plague  prevails  in  men  or  rodents,  every  precaution 
must  be  taken  to  prevent  rats,  fleas,  or  other  vermin 
from  getting  aboard." 

"So  far  as  possible,  passengers  should  avoid  embarking 
at  a  port  where  quarantinable  disease  prevails,  and  com- 


QUARANTINE  REGULATIONS  373 

munication  between  the  vessel  and  shore  should  be  reduced 
to  a  minimum." 

The  regulations  also  indicate  what  kind  of  cargo,  com- 
ing from  or  through  infected  districts,  may  or  may  not  be 
shipped,  and  what  kinds  must  invariably  be  disinfected 
under  any  circumstances. 

As  to  the  passengers,  while  they  are  divided  into  two 
classes,  cabin  and  steerage,  no  person  suffering  from 
plague,  leprosy,  cholera,  smallpox,  yellow  or  typhus 
fever,  scarlet  fever,  measles,  or  diphtheria  or  other  com- 
municable disease  in  epidemic  form  is  allowed  to  ship. 
Steerage  passengers  and  members  of  the  crew  who  have 
been  exposed  to  smallpox  must  be  vaccinated  before 
embarking  unless  they  can  show  proof  of  immunity  by 
former  attack  or  by  satisfactory  vaccination  within  one 
year.  If  the  passengers  or  any  of  the  crew  have  been  ex- 
posed to  typhus  fever  infection,  they  may  not  embark  until 
twelve  days,  and  for  plague,  seven  days,  after  such  expos- 
ure, while  steerage  passengers  and  sailors  from  cholera- 
infected  districts  must  be  detained  for  five  days  in  suitable 
houses  or  barracks  located  where  there  is  no  danger  from 
infection.  Passengers  and  sailors,  who,  in  the  opinion  of 
the  inspecting  officer,  have  been  definitely  exposed  to  the 
infection  of  yellow  fever  (i.  e.,  as  from  a  house  or  locality 
known  to  be  infected),  should  not  be  allowed  to  embark 
for  six  days  after  said  exposure.  No  alien  who  is  a  leper 
should  be  allowed  to  embark  for  the  United  States. 

The  baggage  of  passengers  or  crew  exposed  to  infection 
or  from  infected  ports  should  be  inspected  and,  if  necessary, 
disinfected  and,  in  the  case  of  plague  or  typhus  fever, 
treated  to  destroy  vermin. 

The  same  rules  as  to  detention  and  disinfection  are  to  be 
applied  to  those  coming  from  places  where  the  plague, 
yellow  fever,  or  smallpox  is  prevalent  in  an  epidemic 
form,  and  if  one  of  these  diseases  or  cholera  breaks  out 
in  the  detention  barracks,  there  must  be  a  repetition  of 
the  previous  isolation,  disinfection,  etc.,  dating  from  the 
removal  of  the  last  case.    Cabin  passengers  from  cholera 


374  QUARANTINE 

or  other  infected  ports  or  districts  should  produce  satis- 
factory evidence  as  to  their  exact  place  of  abode  during 
the  five  days  immediately  preceding  embarkation,  and 
if  there  is  any  reason  for  the  belief  that  any  one  of  these 
or  his  baggage  has  been  infected,  such  passenger  is  to  be 
detained  under  medical  inspection  a  sufficient  time  to 
cover  the  period  of  incubation  since  the  last  exposure, 
and  his  baggage  is  to  be  disinfected. 

Every  steerage  passenger  must  also  have  an  inspection- 
card,  stamped  by  the  consular  or  medical  officer,  giving 
name  and  last  permanent  residence  of  passenger,  and  of 
ship  and  port  with  date  of  departure,  etc. ;  and  all  baggage 
of  passengers  must  have  a  label  bearing  the  seal  or  stamp 
of  the  United  States  consular  or  medical  officer,  the  name 
of  port  and  of  the  vessel  carrying  the  baggage,  and  the 
statement  and  date  of  inspection  or  disinfection. 

It  is  evident  that  if  these  regulations  at  foreign  ports, 
together  with  those  required  at  sea — viz.,  rigorous  clean- 
liness and  free  ventilation  of  the  vessel,  daily  inspection 
by  the  ship's  physician,  isolation  of  the  sick,  disinfec- 
tion of  their  clothing,  bedding  and  excreta,  destruction 
of  mosquitoes  and  vermin,  etc. — be  properly  observed, 
there  can  be  but  little  chance  of  the  germs  of  quarantin- 
able  disease  gaining  entrance  to  our  country;  and,  since 
the  duration  of  the  voyage  will  in  most  cases  exceed  the 
period  of  incubation  of  most  of  the  contagious  diseases, 
if  none  of  these  manifest  themselves  on  shipboard  at  sea 
there  will  be  no  need  for  any  detention  at  the  port  of 
entry  beyond  that  which  the  inspecting  officer  stationed 
there  requires  for  the  performance  of  his  duties,  viz., 
to  inspect  the  vessel,  bill  of  health,  crew  and  passengers, 
and  their  lists  and  manifests,  the  ship  physician's  clinical 
record  of  all  cases  treated,  and,  when  necessary,  the  ship's 
log. 

This  inspection  service  is  to  be  maintained  at  every 
domestic  port  throughout  the  year,  and  is  in  force  not 
only  with  respect  to  all  vessels  from  foreign  ports,  but  also 
regarding  any  vessel  with  sickness  on  board,  vessels  from 


*  ENTRY  OF  VESSELS  375 

domestic  ports  where  cholera  or  yellow  fever  prevails,  or 
where  smallpox  or  typhus  fever  prevails  in  epidemic 
form,  vessels  from  foreign  ports  carrying  passengers 
having  entered  a  port  of  the  United  States  without  com- 
plete discharge  of  passengers  or  cargo,  and  vessels  hav- 
ing been  treated  at  national  quarantine  stations  that  are 
located  a  considerable  distance  from  the  port  of  entry 
of  said  vessels.  Moreover,  the  duties  of  the  inspecting 
officer  above  stated  are  only  the  required  minimum  stand- 
ard, and  such  other  regulations  may  be  added  by  legal 
State  or  local  authorities  as  may,  for  special  reasons,  be 
necessary. 

If  the  inspecting  or  health  officer  is  satisfied  that  the 
vessel  is  not  infected  and  all  the  foregoing  requirements 
have  been  complied  with,  he  gives  his  certificate,  to  be 
delivered  to  the  collector  of  customs  of  the  port,  and  no 
vessel  is  permitted  to  land  any  of  its  passengers  or  cargo 
unless  it  have  this  certificate,  together  with  the  bill  of 
health,  etc.,  from  the  port  of  departure,  as  evidence  that 
the  regulations  have  been  properly  observed. 

On  the  other  hand,  if  vessels  arrive  under  the  following 
conditions  they  are  to  be  remanded  by  the  authority  of 
the  Secretary  of  the  Treasury  to  the  nearest  national  or 
other  quarantine  station  where  proper  accommodations 
and  appliances  are  provided  for  the  necessary  disinfection 
and  treatment  of  the  vessel,  passengers,  and  cargo;  and 
only  after  treatment  and  after  obtaining  a  certificate  from 
the  proper  officer  that  the  vessel,  cargo,  and  passengers  are 
each  and  all  free  from  infectious  disease  and  from  danger 
of  conveying  the  same,  can  a  vessel  be  admitted  to  entry 
to  the  ports  named  in  the  certificate. 

The  conditions  under  which  arriving  vessels  are  to  be 
placed  in  quarantine  are  these:  "(a)  With  quarantinable 
disease  on  board  or  having  had  such  disease  on  board 
during  the  voyage,"  the  quarantinable  disease  for  the  pur- 
poses of  these  regulations  being  cholera  (cholerine),  plague, 
yellow  fever,  smallpox,  typhus  fever,  and  leprosy.  (6) 
Any  vessel  which  the  quarantine  officer  considers  infected 


376  QUARANTINE 

with  quarantinable  disease,  (c)  If  arriving  at  a  port 
south  of  the  southern  boundary  of  Virginia  in  the  season  of 
close  quarantine  (April  1  to  November  1)  from  a  tropical 
American  port,  unless  said  port  is  known  to  be  free  from 
yellow  fever,  (d)  Vessels  arriving  at  ports  north  of  this 
line  and  south  of  the  southern  border  of  Maryland,  be- 
tween May  15  and  October  1,  if  from  a  tropical  American 
port,  unless  said  port  is  known  to  be  free  from  yellow 
fever,  (e)  Vessels  arriving  at  a  southern  port,  referred 
to  in  paragraphs  (c)  and  (d)  during  the  season  of  close 
quarantine  for  such  ports,  via  a  northern  port,  when  from 
a  port  known  to  be  infected  with  yellow  fever,  unless  six 
days  have  elapsed  since  the  fumigation  of  the  vessel 
in  such  northern  port,  and  a  certificate  be  presented  from 
the  quarantine  officer  at  such  northern  port,  or  an  ac- 
credited medical  officer  of  the  United  States.  (/)  In  the 
case  of  vessels  arriving  at  a  northern  port  without  sickness 
on  board  from  ports  where  yellow  fever  prevails,  the 
personnel  shall  be  detained  under  observation  at  quaran- 
tine to  complete  six  days  from  the  port  of  departure. 
(g)  Towboats  and  other  vessels  having  had  communica- 
tion with  vessels  subject  to  quarantine  shall  themselves 
be  quarantined  if  they  have  been  exposed  to  infection." 

'^  Vessels  engaged  in  the  fruit  trade  may  be  admitted 
to  entry  without  detention,  provided  they  have  complied 
in  all  respects  with  the  special  rules  and  regulations  made 
by  the  Secretary  of  the  Treasury  with  regard  to  vessels 
engaged  in  said  trade. "^ 

There  are  ten  national  quarantine  stations  and  a  number 
of  others  under  State  or  municipal  control;  those  which 
have  steam  disinfection  chambers  and  other  efficient 
equipments  are  located  at  Portland,  Me.;  Boston,  New 
York,  Sandy  Hook,  Delaware  Breakwater,  Reedy  Island 
in  the  Delaware  River,  Cape  Charles,  Baltimore;  Wil- 
mington, N.  C;  Savannah,  Blackbeard  Island,  Ga.; 
Charleston,    Dry   Tortugas,    Key   West,    Mullet    Keys, 

^  Quarantine  Laws  and  Regulations  of  the  United  States. 


ENTRY  OF  VESSELS  377 

Pensacola,  Mobile,  Chandeleur  Islands,  New  Orleans, 
Galveston,  San  Diego,  San  Francisco,  and  Port  Townsend; 
the  ten  national  ones  being  included  in  the  list. 

The  essential  requisites  for  a  properly  equipped  quar- 
antine station,  after  the  selection  of  a  proper  location — 
which  should  be  convenient,  but  not  in  the  line  of  future 
city  growth — are  the  following:^  (1)  A  boarding  station, 
including  boat-house  and  boatmen's  quarters.  (2)  A  board- 
ing-boat, preferably  a  steamer  or  motor  launch.  (3)  An 
anchorage  for  the  detention  of  infected  vessels.  It  should 
be  safely  out  of  the  track  of  commerce,  convenient  but  not 
too  close  to  the  main  quarantine  establishment,  sheltered, 
and  with  good  holding  ground  for  anchors.  (4)  A  fumiga- 
tion steamer  with  appliances  for  generating  and  forcing 
sulphurous  acid  (or  formaldehyde)  gas  into  vessels,  and 
with  tanks  and  pumps  for  disinfecting  solutions.  (5)  A 
wharf,  in  water  at  least  twenty  feet  deep,  and  upon  which 
are  constructed  a  w^arehouse,  tanks  for  disinfecting  solu- 
tions, and  a  disinfecting  house  containing  steam  dis- 
infecting chambers.  (6)  A  lazaretto  or  hospital  for  the 
treatment  of  contagious  diseases.  (7)  A  hospital  for  non- 
contagious diseases.  (8)  Barracks  or  quarters  for  the 
detention  in  groups  for  those  who  may  have  been  exposed 
to  contagion  or  infection.  (9)  Quarters  for  medical  officers. 
(10)  A  cremation  furnace. 

When  a  vessel  is  remanded  to  quarantine  by  the  in- 
specting officers  at  a  port  of  entry,  its  treatment  and  that 
of  its  cargo  and  passengers  will  depend  largely  upon  the 
disease  with  which  it  is  infected,  being  more  severe  if  the 
latter  is  cholera  or  yellow  fever.  In  case  of  infection  by 
either  of  these  diseases  the  vessel  is  at  once  sent  to  the 
anchorage,  and  must  remain  there  until  the  passengers 
have  been  discharged  and  the  vessel  purified,  and  in  any 
case  there  must  be  no  direct  communication  allowed 
between  quarantine  or  a  vessel  in  quarantine  and  any 
person  or  place  outside,  except  under  supervision  of  the 
quarantine  officer. 

1  Roh6'8  Hygiene. 


378  QUARANTINE 

Moreover,  if  cholera  has  occurred  on  board,  all  passen- 
gers and  all  of  the  crew,  except  such  as  are  necessary  to 
care  for  her,  must  be  at  once  removed,  the  sick  to  be  sent 
to  the  lazaretto  or  hospital,  others  specially  suspected 
must  be  carefully  isolated,  and  the  remainder  separated 
into  small  groups,  between  which  there  must  be  no  com- 
munication. Those  who  are  especially  liable  to  convey 
infection  must  be  bathed  and  furnished  with  sterile  cloth- 
ing before  entering  the  barracks,  and  no  articles  capable 
of  carrying  infective  matter,  especially  food  and  water, 
should  be  taken  into  the  barracks.  All  baggage  or  effects 
of  passengers  or  crew  that  has  been  exposed  to  the  infec- 
tion, all  articles  of  the  cargo  likely  to  be  infected,  and  all 
furniture,  living  apartments,  and  such  other  portions  of 
the  vessel  as  may  possibly  retain  or  convey  infection  must 
be  disinfected.  The  water-supply  must  be  changed  at 
once,  the  tanks  thoroughly  disinfected  by  steam  or 
potassium  permanganate  solution,  and  refilled  with  water 
from  a  pure  source  or  with  water  recently  boiled.  The 
water-ballast  of  a  cholera-infected  vessel,  or  of  one  from 
a  cholera-infected  port,  should  never  be  discharged  in 
fresh  or  brackish  water  without  previous  disinfection,  and 
the  ballast  tanks  should  be  refilled  with  sea-water  or  else 
be  disinfected  before  refilling.  Nothing  is  to  be  thrown 
overboard  from  a  cholera-infected  vessel  in  quarantine, 
but  everything  that  is  to  be  destroyed,  even  deck-sweep- 
ings, should  be  burned  in  the  furnace. 

The  special  regulations  on  account  of  yellow  fever 
involve  a  careful  visual  and  thermometer  inspection  of 
all  persons,  the  immediate  disembarking  and  removal  of 
the  sick,  screened  against  the  access  of  stegomyia  mos- 
quitoes, to  a  place  of  isolation,  and  a  similar  isolation 
in  screened  apartments  of  all  persons  with  a  temperature 
above  37.6°  C.  Other  persons  shall  be  disembarked,  if 
possible,  and  shall  be  subjected  to  observation  for  six 
days,  dating  from  the  last  possible  exposure.  The  ship 
shall  be  moored  at  least  200  meters  from  an  inhabited 
shore,  and  shall  be  fumigated  for  the  destruction  of  mos- 


THEATMENT  OF  INFECTED  VESSELS  379 

quitoes  before  the  discharge  of  the  cargo,  if  possible.  If 
this  is  not  possible,  the  discharge  of  cargo  shall  be  under 
the  supervision  of  the  quarantine  officer,  preferably  by 
the  employment  of  immune  persons  for  the  discharging. 
If  non-immunes  are  employed,  they  must  be  kept  under 
supervision  during  the  discharging  and  for  six  days  after 
the  last  day  of  exposure  on  board.  For  the  destruction 
of  mosquitoes  there  shall  be  a  complete  and  simultaneous 
fumigation  of  all  parts  of  the  vessel,  preferably  by  sulphur 
dioxide. 

With  respect  to  plague,  on  board  ships  on  which  this 
disease  has  occurred,  either  in  men  or  rats,  there  must 
be  careful  inspection,  immediate  disembarking  and  iso- 
lation of  the  sick,  and  the  destruction  of  all  rats  on  ship- 
board as  soon  as  practicable,  the  cargo  being  partially  or 
completely  removed,  if  necessary  to  this  end,  and  proper 
precautions  being  taken  to  prevent  rats  getting  ashore. 
Seven  days  is  considered  as  the  incubation  period  of  plague, 
and  all  persons  shall  be  held  under  observation  for  at 
least  five  days.  Soiled  linen,  personal  effects  and  belong- 
ings of  crew  or  passengers  considered  to  be  infected  shall 
be  disinfected  and  rendered  free  from  vermin,  and  "in 
all  cases  the  quarantine  oflficer  shall  assure  himself  that 
the  vessel  is  free  from  rats  and  vermin  before  granting 
"free  pratique." 

For  typhus  fever  twelve  days  is  considered  as  the  incu- 
bation period,  and  the  efforts  for  disinfection  are  chiefly 
directed  toward  the  destruction  of  vermin.  The  sick 
are,  of  course,  to  be  removed  and  isolated,  and  those 
exposed  to  infection  detained  under  observation  for  the 
incubation  period.  With  regard  to  smallpox,  all  persons 
who  have  been  exposed  to  infection  on  any  vessel  which 
arrives  with,  or  has  had,  this  disease  on  board  during  the 
voyage,  must  be  vaccinated  or  detained  in  quarantine 
not  less  than  fourteen  days  since  the  last  exposure,  unless 
they  can  show  satisfactory  evidence  of  successful  vaccina- 
tion within  one  year  or  of  having  had  smallpox.  Living 
compartments  and  other  parts  of  the  vessel  and  baggage 


380  •    QUARANTINE 

and  belongings  of  crew  and  passengers  that  have  been 
exposed  to  infection  must  be  disinfected;  but  if  the  dis- 
ease has  been  properly  isolated  and  sufficient  precautions 
taken  to  prevent  the  spread  of  the  disease,  the  vessel  is 
only  detained  in  quarantine  long  enough  for  the  removal 
of  the  sick,  disinfection  of  compartments,  baggage,  etc., 
and  the  vaccination  of  exposed  persons,  as  indicated  above. 

"Vessels  arriving  at  quarantine  with  leprosy  on  board 
shall  not  be  granted  "free  pratique"  until  the  leper  with  his 
or  her  baggage  has  been  removed  from  the  vessel  to  the 
quarantine  station.  No  alien  leper  shall  be  landed.  If 
the  leper  is  an  alien  passenger  and  the  vessel  from  a  for- 
eign port,  action  will  be  taken  as  provided  by  the  im- 
migration laws  and  regulations  of  the  United  States.  If 
the  leper  is  an  alien  and  a  member  of  the  crew,  and  the 
vessel  is  from  a  foreign  port,  said  leper  shall  be  detained 
at  quarantine  at  the  vessel's  expense,  until  taken  aboard 
by  the  same  vessel  when  outward  bound." 

The  disinfection  of  the  holds  of  vessels  is  to  be  by 
mechanical  cleansing,  by  an  acid  bichloride  of  mercury 
solution  (1  to  800)  applied  under  pressure,  and  by  sul- 
phurous acid-gas  (10  per  cent,  per  volume  strength)  for 
from  twenty-four  to  forty-eight  hours.  All  ballast  must 
be  discharged  or  disinfected  before  the  disinfection  of  the 
hold,  and  all  solid  ballast  must  be  disinfected  before  being 
discharged  into  fresh  water.  The  steerage  and  forecastle 
are  to  be  disinfected  by  live  steam,  if  possible,  for  at  least 
half  an  hour,  and,  if  not,  by  sulphur  dioxide  and  bichlo- 
ride solution,  as  was  the  hold.  Baggage,  bedding,  carpets, 
\  etc.,  are  to  be  removed  with  caution  and  to  be  disinfected 
by  steam  or  by  boiling,  and,  finally,  all  woodwork  of  the 
vessel  is  to  be  thoroughly  cleansed  mechanically  and  then 
washed  with  an  acid  bichloride  of  mercury  solution 
(1  to  1000). 

The  following  Rules  for  the  application  of  disinfectants 
in  quarantine  work  were  issued  as  part  of  the  quarantine 
regulations  of  the  United  States  Government  on  October 
20,  1910: 


DISINFECTANTS  IN  QUARANTINE  WORK      381 


APPLICATION   OF  DISINFECTANTS  IN    QUARANTINE 

WORK. 

The  holds  of  iron  vessels,  empty,  shall  be  disinfected 
by  either: 

(a)  Sulphur  dioxide  generated  by  burning  sulphur,  5 
pounds  per  1000  cubic  feet  of  air  space,  or  liberated  from 
10  pounds  of  liquid  sulphur  dioxide,  sufficient  moisture 
being  present  in  both  cases;  time  of  exposure,  twenty-four 
hours. 

(6)  Washing  with  a  solution  of  bichloride  of  mercury, 
1  to  1000. 

Holds  of  wooden  vessels,  empty,  shall  be  disinfected 
by: 

(a)  Sulphur  dioxide  in  the  manner  prescribed  above, 
followed  by: 

(6)  Washing  with  a  solution  of  bichloride  of  mer- 
cury. 

Holds  of  cargo  vessels,  when  cargo  cannot  be  removed, 
shall  be  disinfected  in  so  far  as  possible  by  sulphur  dioxide, 
not  less  than  4  per  cent,  per  volume  strength,  and  where 
possible  this  should  be  generated  from  a  furnace  to 
minimize  danger  of  fire  in  cargo. 

Living  apartments,  cabins,  and  forecastles  of  vessels 
shall  be  disinfected  by  one  or  more  of  the  following 
methods: 

(a)  Sulphur  dioxide;  the  destructive  action  of  the  gas 
on  property  being  borne  in  mind. 

(6)  Formaldehyde-gas. 

(c)  Washing  with  solution  of  bichloride  of  mercury, 
1  to  1000,  or  5  per  cent,  solution  of  formalin,  or  5  per  cent', 
solution  of  carbolic  acid,  preference  being  given  to  carbolic 
acid  for  application  to  polished  woods,  bright  metals, 
and  other  objects  injured  by  metallic  salts. 

The  forecastle,  steerage,  and  other  living  apartments 
in  bad  sanitary  condition  must  be  disinfected  by  method 
(a)  followed  by  method  (c). 


382  QUARANTINE 

Mattresses,  pillows,  and  heavy  fabrics  are  to  be  disin- 
fected by: 
(a)  Boiling. 
(6)  Flowing  steam,  i.  e.,  steam  not  under  pressure. 

(c)  Steam  under  pressure. 

(d)  Steam  in  a  special  apparatus  with  vacuum  attach- 
ment. 

Clothing,  fabrics,  textiles,  curtains,  hangings,  etc.,  may 
be  treated  by  either  of  the  above  methods  from  (a)  to  (d) 
inclusive,  as  circumstances  may  demand,  or  by  formal- 
dehyde-gas or  sulphur  dioxide  where  the  article  is  of  a 
character  which  will  not  be  damaged  by  sulphur  dioxide. 

Articles  injured  by  steam,  such  as  leather,  furs,  skins, 
rubber,  trunks,  valises,  hats  and  caps,  bound  books,  silks, 
and  fine  woolens  should  not  be  disinfected  by  steam. 
Such  articles  should  be  disinfected  by  formaldehyde-gas 
or  by  any  of  the  agents  allowed  in  these  regulations  which 
may  be  applicable  thereto.  Those  which  will  be  injured 
by  wetting  should  be  disinfected  by  a  gaseous  agent. 

Clothing,  textiles,  and  baggage,  clean  and  in  good  con- 
dition, but  suspected  of  infection,  can  be  efficiently  and 
least  injuriously  disinfected  by  formaldehyde-gas,  gen- 
erated by  one  of  the  methods  previously  described. 

Textiles  which  are  soiled  with  the  discharges  of  the  sick 
or  presumably  are  deeply  infected,  must  be  disinfected  by: 

(a)  Boiling.  , 

(6)  Steam. 

(c)  Immersion  in  one  of  the  germicidal  solutions. 

Cooking  and  eating  utensils  are  always  to  be  disinfected 
by  immersion  in  boiling  water  or  by  steam. 

As  to  the  passengers  and  others  who  have  been  isolated 
in  groups,  they  are  to  be  inspected  twice  daily  by  the 
physician  and  remain  under  his  constant  surveillance, 
and  can  have  no  communication  with  anyone  in  a  differ- 
ent group  or  outside  of  quarantine,  except  through  the 
quarantine  officer.  The  water-supply  and  food-supply 
are  to  be  strictly  guarded,  and  are  issued  to  each  group 
separately.    The  latter  is  to  be  simple  in  character  and 


DISINFECTION  OF  VESSELS  383 

abundant  in  quantity,  but  no  fruit  is  to  be  permitted. 
Strict  cleanliness  is  to  be  enjoined,  disinfection  wherever 
necessary,  and,  in  case  quarantinable  disease  appears 
in  any  group,  the  sick  will  be  immediately  removed  to 
the  hospital,  and  the  rest  of  the  group  bathed  and  their 
effects  disinfected,  and  all  of  them  removed  to  other 
quarters,  if  possible.  None  are  to  leave  quarantine  until 
the  end  of  the  incubation  period  of  the  disease  in  question, 
dating  from  the  last  exposure  to  infection  and  the  final 
disinfection  of  such  effects  as  were  taken  to  barracks; 
and  no  convalescent  may  leave  quarantine  until  a  bac- 
teriological examination  shows  him  to  be  free  from 
infection. 

As  has  been  stated,  the  treatment  of  vessels  infected 
by  some  diseases  is  not  necessarily  so  severe  as  that  of 
others,  but  in  each  case  every  effort  is  made  to  allow  no 
loop-hole  for  the  entrance  of  infection  into  the  country, 
and  no  vessel  may  leave  quarantine  until  she  has  a  certifi- 
cate from  the  health  (quarantine)  officer  that  she  has  in 
all  respects  complied  with  the  quarantine  regulations,  and 
that,  in  his  opinion,  she  will  not  convey  quarantinable 
disease.    She  is  then  said  to  be  granted  free  pratique. 

The  law  further  provides  that  "  when  practicable,  alien 
immigrants  arriving  at  Canadian  and  Mexican  ports, 
destined  for  the  United  States,  shall  be  inspected  at  the 
port  of  arrival  by  the  United  States  consular  or  medical 
officer,  and  be  subjected  to  the  same  sanitary  restrictions 
as  are  called  for  by  the  rules  and  regulations  governing 
United  States  ports;  that  inspection-cards  will  be  issued 
by  the  United  States  officer  at  the  port  of  arrival  to  all 
such  immigrants,  and  labels  affixed  to  their  baggage,  as 
is  required  at  foreign  ports."  Where  such  immigrants 
are  not  inspected  at  the  port  of  arrival  they  shall  enter 
the  United  States  only  at  certain  designated  points  on  the 
frontier,  and  then  only  after  such  inspection,  detention, 
disinfection,  vaccination,  etc.,  as  may  be  necessary  or 
required  by  the  officers  there  stationed. 

There  is  also  provision  for  the  inspection  of  State  or 


384  QUARANTINE 

local  quarantines  from  time  to  time  by  the  Supervising 
Surgeon-General  of  the  U.S.  Public  Health  Service,  or  by 
any  officer  of  that  service  detailed  by  him;  and  for  the 
observance  at  all  quarantines  of  such  additional  rules  and 
regulations  as  may  from  time  to  time  be  promulgated  by 
him. 

INLAND  QUARANTINE. 

Under  this  heading  may  be  considered  the  means  that 
may  be  employed  to  prevent  an  epidemic  extending  from 
one  locality  or  district  to  another,  although  the  principle 
and  aims  are  practically  the  same  as  those  of  maritime 
quarantines,  viz.,  to  define  certain  boundaries  beyond 
which  no  person  or  thing  capable  of  carrying  infection  may 
pass,  and  to  establish  certain  points  of  ingress  or  egress 
on  these  boundaries  where  there  may  be  the  necessary 
detention,  inspection,  disinfection,  etc. 

The  sanitary  cordon  "consists  of  a  line  of  guards,  mili- 
tary or  civil,  thrown  around  a  district  or  locality,  either 
to  protect  the  same  from  the  surrounding  country  when 
infected,  or  to  protect  the  surrounding  country  from  the 
infected  district  or  locality."  "It  is  not  intended  to 
bottle  up  all  the  people  who  are  caught  within  an  infected 
district,  but,  on  the  contrary,  is  intended  as  a  means  of 
exit  to  those  who  will  not  carry  with  them  contagious 
diseases  to  the  people  beyond. "^  It  may  be  single  or 
double;  in  the  latter  case  the  inner  line  closely  encircles 
the  well-defined  infected  locality,  and  the  outer  line  the 
whole  suspected  territory.  This  latter  may  be  removed 
as  soon  as  it  is  evident  that  the  space  between  it  and  the 
inner  line  is  not  infected.  To  be  efficient  the  cordon  must 
be  so  guarded  that,  even  though  it  be  many  miles  in 
length,  no  unauthorized  person  may  pass  through  it, 
while  at  certain  places  upon  it  camps  of  probation  or 
detention  must  be  established,  where  all  persons  coming 
from  the  infected  locality  may  be  kept  under  observation 

^  Roh6's  Hygiene,  "Quarantine." 


INLAND  QUARANTINE  385 

for  a  time  equal  to  the  period  of  incubation  of  the  disease 
in  question.  These  camps  of  probation  or  detention 
are  to  be  distinguished  from  the  camps  of  refuge,  which 
were  first  suggested  by  Surgeon-General  Woodward  in 
1878,  and  which  are  "simple  residence  camps  established 
to  receive  the  population  of  an  infected  community 
when  it  has  been  determined  to  depopulate  the  infected 
district." 

At  these  camps  of  detention  provision  must  be  made 
for  inspecting  every  person  and  disinfecting  all  baggage 
before  entering  camp,  for  isolating  the  occupants  and 
housing  and  feeding  them  in  the  most  comfortable  and 
sanitary  manner  during  the  detention,  for  inspections 
twice  or  thrice  daily,  for  the  isolation  and  care  of  the  sick 
in  hospitals  at  a  safe  distance  from  camp,  and  for  the 
issuance  of  a  certificate  granting  "free  pratique"  when 
the  period  of  detention  is  over. 

A  notable  instance  of  the  sanitary  cordon  was  that  about 
the  city  of  Brownsville,  Texas,  and  along  the  Rio  Grande, 
in  1882;  and  of  a  detention  camp,  that  at  Camp  Perry, 
Florida,  in  1888. 

In  addition  to  these  measures  it  may  be  necessary  or 
advisable  to  establish  a  railroad  quarantine,  as  follows: 
"At  certain  convenient  points,  which  will  be  the  only 
points  of  egress  by  rail  from  the  infected  district,  an 
inspection  service  and  disinfecting  station  are  to  be 
maintained  throughout  the  epidemic.  Here  all  the 
baggage  and  freight  are  to  be  properly  disinfe^cted  and  all 
passengers  are  to  be  examined  by  the  official  inspectors; 
if  the  latter  are  from  the  infected  locality,  or  have  not  a 
certificate  from  some  recognized  health  officer  as  to  where 
they  have  been  for  the  previous  days  corresponding  to  the 
incubative  period  of  the  disease,  they  are  to  be  at  once 
remanded  to  the  nearest  camp  of  probation,  there  to 
undergo  the  necessary  detention.  Moreover,  it  may  seem 
advisable  to  prevent  any  passenger  cars  going  beyond  the 
infected  district,  and  to  disinfect  all  freight  and  baggage 
cars  that  do  so." 
25 


386  QUARANTINE 

Local  and  House  Quarantine. — There  may  also  be  local 
or  house  quarantines  established  by  municipal  boards  of 
health  or  other  authorities  to  prevent  not  only  the  family 
or  attendants  of  the  sick  from  mingling  with  the  rest  of 
the  community,  but  also  to  keep  injudicious  outsiders 
from  spreading  the  infection  through  unwise  visitations. 
And  though  such  isolation  may  appear  at  times  a  hard- 
ship to  certain  individuals  and  to  be  unduly  severe,  one 
should  not  forget  the  great  cost  to  all  concerned  of  epi- 
demics once  inaugurated,  nor  that  it  is  only  by  such 
stringent  measures  that  we  shall  be  able  to  eradicate  the 
infectious  maladies  from  our  communities. 

Vaccination. — ^The  foregoing  remarks  apply  likewise 
to  other  prophylactic  measures,  such  as,  for  example, 
vaccination.  Within  the  last  few  years  there  have  been 
many  epidemics  of  smallpox  throughout  the  whole 
country,  the  extent  and  spread  of  which  were  due  to  a 
very  general  neglect  to  secure  the  protection  afforded  by 
vaccination.  -To  controvert  those  who  assert  that  this 
prophylactic  measure  is  of  no  value,  the  following  statistics 
are  quoted  from  McFarland,  from  Welch  and  Schamberg, 
and  from  Harrington:  Prior  to  the  adoption,  April  1, 
1875,  of  the  German  law  requiring  vaccination  at  birth 
and  at  the  tenth  year,  the  annual  mortality  in  Prussia, 
from  1816  to  1870  was  from  7.32  to  66  per  100,000  of 
population;  in  1871  it  was  243.2,  and  in  1872  it  was  262.67, 
owing  to  the  introduction  of  French  prisoners.  Since 
then  there  has  been  no  epidemic,  but  from  1875  to  1886 
the  average  annual  mortality  was  1.91  per  100,000  and 
the  lowest  0.36.  On  the  other  hand,  from  1870  to  1895 
over  20,000  died  from  smallpox  in  Paris  alone,  where 
vaccination  is  not  compulsory. 

In  the  following  table,  note  that  vaccination  was  com- 
pulsory in  the  first  five  cities  and  not  enforced  in  the 
other  four: 


INLAND  QUARANTINE  387 

Death-rate  for  Smallpox. 

(in  100,000  of  population— 1875-1889). 

<     Berlin 1.16 

Hamburg 0.74 

Breslau 1.11 

Munich 1 .45 

Dresden 1.03 

Paris 26.24 

St.  Petersburg 35 .  82 

Vienna 64.90 

Prague  147.90 

According  to  Harrington,  in  the  Sheffield  epidemic  of 
1887-88,  1.55  per  cent,  of  vaccinated  and  9.7  per  cent, 
of  un vaccinated  were  attacked,  the  death-rate  among  the 
former  being  0.7  and  among  the  latter  48  per  1000. 
Among  children  under  ten  the  rate  of  attack  was  5  and 
101  per  1000  respectively  for  vaccinated  and  unvaccinated, 
and  the  death-rate  was  0.09  and  44  per  1000.  From  the 
statistics  of  this  epidemic  w^e  have: 

Rates  of  Attack  per  1000  Persons. 

Persons  not  vaccinated 94 .  00 

Persons  once  vaccinated 19 .  00 

Persons  twice  vaccinated 3 .  00 

Death-rates  per  1000  Persons. 

Persons  not  vaccinated 51.00 

Persons  once  vaccinated 1 .  00 

Persons  twice  vaccinated 0.08 

The  same  authority  states  that  a  "successful  primary 
vaccination  within  three  days  after  exposure  to  existing 
cases  of  smallpox  will  prevent  the  development  of  the 
disease,  and  as  late  as  the  fifth  or  sixth  day  will  either 
prevent  or  modify  an  attack."  So  that  epidemics,  even 
when  well  under  way,  can  be  checked  by  wholesale  vacci- 
nation. 

However,  vaccination  should  be  repeated  from  time  to 
time,  especially  when  there  is  danger  of  infection.  In 
Philadelphia,  in  1901-04,  not  one  of  the  350Q  smallpox 
patients  treated  at  the  Municipal  Hospital  had  been  sue- 


388  QUARANTINE 

cessfully  vaccinated,  as  evidenced  by  the  scar,  within  four 
years  of  the  attack,  and  this  in  spite  of  the  fact  that 
about  500,000  persons,  or  one-third  of  the  city's  popula- 
tion, were  vaccinated  during  this  epidemic. 

From  the  data  of  this  hospital  Welch  and  Schamberg 
compiled  the  following:^ 

Percentage 
Cases.  Deaths.  of  deaths. 

Vaccinated  in  infancy,  good  scars  .      .     2335  152  6 .  50 

Vaccinated  in  infancy,  fair  scars      .  1105  135  12.21 

Vaccinated  in  infancy,  poor  scars    .      .      1524  345  22.64 


Postvaccinal  cases 4964  632  12 .  53 

Unvaccinated 3687  1542  41.82 


Total 8651  2174  25.13 

Again  in  the  same  hospital,  "during  a  period  of  thirty- 
four  years,  in  which  time  over  9000  cases  of  smallpox 
have  been  treated,  not  a  physician,  nurse,  or  attendant 
who  had  been  successfully  vaccinated  or  revaccinated  prior 
to  going  on  duty,  contracted  the  disease." 

Surely,  with  modern  statistics  such  as  the  foregoing  at 
hand,  it  is  not  necessary  to  recall  the  excessively  high 
mortalities  of  the  eighteenth  century  prior  to  Jenner's 
discovery,  amounting  to  half  a  million  or  more  annually 
in  Europe,  to  convince  intelligent  persons  of  the  great 
value  of  this  one  method  of  prophylaxis,  and  yet  legal 
compulsion  seems  to  be  necessary  to  secure  its  general 
employment. 

In  the  preceding  pages  the  author  has  attempted  to  present  briefly 
the  principles  and  the  regulations  of  quarantine  as  practised  in  the 
United  States  at  the  present  time;  but  the  reader  is  referred  for  further 
details  to  the  extremely  interesting  and  valuable  chapter  on  the  subject 
in  Rohe's  Text-book  of  Hygiene,  by  the  late  Dr.  Walter  Wyman,  the 
former  Supervising  Surgeon-General  of  the  Marine-Hospital  and  Public 
Health  Service. 

1  Acute  Contagious  Diseases,  page  55. 


CHAPTER  XII. 
THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE. 

The  waste  from  dwellings  is  of  three  kinds:  house- 
sweepings  and  the  ashes  from  fires;  the  waste  from 
kitchens,  scraps  of  food,  etc.,  commonly  known  as  gar- 
bage, and  sewage,  the  most  important,  consisting  as  it 
does  of  the  solid  and  liquid  excreta  of  the  body  together 
with  waste  w^ater  from  wash-tubs,  bath-tubs,  kitchens, 
laundries,  etc. 

Ashes  alone  have  little  effect  upon  the  health,  except 
that  they  absorb  moisture  readily,  and  if  allowed  to 
accumulate  in  a  cellar  may  do  much  to  keep  it  damp  and 
mouldy.  For  the  same  reason,  if  they  be  mixed  with 
refuse  vegetable  matters,  putrefaction  is  favored  and 
noxious  emanations  given  off.  The  dust  from  ash  heaps 
may  also  be  carried  into  the  house  and  largely  increase 
the  solid  impurities  of  the  air  therein.  Consequently, 
ashes  should  be  frequently  and  regularly  removed  from 
the  premises. 

Kitchen  garbage  readily  decays,  and  if  allowed  to 
remain  in  the  vicinity  of  the  house  may  pollute  both  the 
air  and  soil  about  it;  but  inasmuch  as  it  has  some  value 
as  a  food  for  animals,  there  is  usually  no  difficulty  in  the 
smaller  communities  in  having  it  removed  by  scavengers 
without  expense  or  delay.  Care  must  be  had,  however, 
that  this  is  done  properly  and  that  all  receptacles  are  kept 
in  as  cleanly  a  condition  as  possible.  Most  large  cities 
now  find  it  safer  to  collect  and  cremate  the  garbage  at  the 
expense  of  the  municipality,  rather  than  to  allow  private 
individuals  to  keep  for  its  consumption  large  numbers  of 
animals  within  or  near  the  city  limits.    Even  though  the 

(389) 


390     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

former  plan  be  the  more  costly,  experience  shows  that  this 
garbage  may  and  should  be  consumed  in  properly  arranged 
crematories  at  convenient  locations  without  annoyance 
to  the  residents  of  the  vicinity,  thus  saving  the  expense 
and  time  necessary  for  conveying  the  garbage  beyond  the 
municipal  limits. 

The  kind  of  waste  to  which  we  give  the  name  sewage 
is,  however,  of  more  importance  to  sanitarians,  since  it  is 
always  a  possible  factor  in  the  production  of  disease,  and 
since  it  presents  the  greater  difficulties  in  respect  to  its 
removal  from  dwellings  and  the  ultimate  disposal  of  it. 

In  addition  to  the  substances  already  named  and  which 
usually  come  from  dwelling-houses,  sewage  may  contain 
the  liquid  excreta  from  stables,  the  refuse  from  factories 
of  all  kinds,  the  drainage  from  polluted  soils,  and  the 
excess  of  rain-water  not  taken  up  by  evaporation  or 
retained  in  the  soil.  Its  composition  must  therefore  be 
always  complex  and  variable,  but  there  will  be  practi- 
cally always  present  in  it  sodium  chloride,  ammonia, 
carbon  monoxide  and  dioxide,  hydrogen  and  ammonium 
sulphide,  fetid  and  decomposing  organic  matter,  and 
myriads  of  bacteria.  Fresh  sewage  will  not  be  so  offen- 
sive to  the  senses  as  that  in  which  putrefaction  has 
commenced,  nor  will  the  gases  arising  from  it  be  so  dan- 
gerous to  health.  Frankland  has  shown  that  "solid  or 
liquid  matter  is  not  likely  to  be  scattered  into  the  air  from 
the  sewage  itself  by  any  agitation  it  is  likely  to  undergo 
until  gas  begins  to  be  generated  in  it;'^  and  it  is  really 
doubtful  whether  the  air  of  a  properly  constructed  and 
well-ventilated  sewer  can  be  shown  to  contain  a  harmful 
excess  of  injurious  gases  and  organisms.  However,  it 
is  essential  that  sewage  should  be  removed  from  the 
premises  of  a  dwelling  as  soon  as  possible  after  its  pro- 
duction and  before  decomposition  begins. 

When  the  above-mentioned  constituents  of  sewage  are 
to  be  disposed  of  collectively,  the  water-carriage  system 
is  usually  the  best.  Although  the  pneumatic  system 
(wherein  air-tight  pipes  extend  from  the  dwellings,  etc., 


SEWAGE  391 

to  resetvoirs  from  which  the  air  is  periodically  exhausted 
and  the  sewage  thus  drawn  into  them)  would  seem  to  be 
advantageous  where  the  topographical  conditions  do  not 
permit  of  natural  drainage,  it  is  always  subject  to  the 
danger  of  breaks  occurring  and  destroying  the  action,  and 
seems  to  have  been  practically  successful  in  but  few 
instances. 

A  modification  of  the  pneumatic  system  which  seems 
to  be  more  successful  and  practical  is  the  Shone  or  ejector 
system.  In  this  the  sewage  is  conducted  by  gravity 
through  suitable  drains  to  convenient  ejector  stations  or 
tanks,  whence  it  is  forced  by  means  of  compressed  air  to 
the  irrigation  fields  or  other  places  of  ultimate  disposal. 
The  system  has  been  in  successful  operation  in  Arad, 
Hungary,  since  1896,  the  plant  disposing  of  the  sewage 
of  20,000  persons  from  five  ejector  stations  at  a  working 
cost,  excluding  interest  and  sinking  fund,  of  about  25s. 
($6.25)  per  day.^ 

On  the  other  hand,  where  house  refuse  only  is  to  be 
considered,  and  where  the  waste- water  can  be  kept  from 
the  other  parts  of  the  sewage,  or  where  the  water-supply, 
the  physical  conditions,  or  the  cost  of  constructing  the 
necessary  sewers  prevent  the  use  of  the  water-carriage 
method,  recourse  should  be  had  to  the  pail  or  earth-closet 
system.  The  use  of  primitive  privy-vaults  or  cesspools 
is  most  insanitary  and  dangerous,  and  should  be  con- 
demned in  almost  every  instance.  Where  the  necessity 
for  one  of  the  latter  seems  imperative,  it  should  be  made 
absolutely  water-tight,  so  that  none  of  the  contents  may 
escape  to  pollute  the  surrounding  soil  and  soil-air  or  to 
contaminate  the  ground-water  in  the  neighborhood. 
Moreover,  the  pits  should  be  properly  ventilated  and 
should  be  cleaned  out  regularly  and  often,  which  may  be 
done  without  offence  by  some  form  of  odorless  excavat- 
ing apparatus,  such  as  is  now  commonly  used. 

The  daily  addition  of  a  solution  of  chlorinated  lime  or 

»  American  Year-book  of  Medicine  for  1900,  pp.  549  and  550. 


392      THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

milk  of  lime  or  of  sulphate  of  iron,  to  the  extent  of  about 
two  quarts  for  each  person  using  the  cesspool,  will  do 
much  in  the  way  of  checking  bacterial  growth,  even 
though  it  does  not  actually  disinfect  the  contents,  and 
will  largely  prevent  the  offensive  odors  of  putrefaction 
from  such  accumulations.  It  should  be  noted  that  the 
contents  of  such  a  vault,  or  of  a  simple  pit  in  the  earth, 
undergo  putrefaction  rather  than  natural  decomposition, 
if  no  antiseptic  be  used,  because  of  the  lack  of  sufficient 
oxygen  supply  and  of  the  adjunct  action  of  the  nitrifying 
bacteria  which  are  found  only  in  the  uppermost  layers  of 
the  soil. 

It  is  also  probable  that  many  disease  germs,  particularly 
those  of  diphtheria  or  typhoid  fever,  will  survive  and 
multiply  better  in  the  contents  of  such  a  vault  than  in 
sewage  or  refuse  treated  by  the  methods  to  be  hereafter 
described. 

In  the  pail  system  the  more  solid  waste  matters,  and 
especially  human  excreta,  are  collected  in  a  suitable  pail 
or  tub,  which,  holding  only  a  limited  amount,  must  of 
necessity  be  removed  and  emptied  regularly  and  often. 
If  the  outbuildings  used  for  this  purpose  be  kept  clean 
and  properly  ventilated,  such  a  system  will  be  both 
economical  and  healthful. 

Advantage  may  here  be  taken  of  the  great  deodorizing, 
nitrifying,  and  oxidizing  power  of  fine,  dry  earth,  and 
various  forms  of  earth-closets  have  been  devised  to  be  used 
in  conjunction  with  the  pail  system.  If  a  quantity  of  dry, 
sifted  earth,  in  bulk  about  twice  that  of  the  dejecta,  is 
thrown  upon  the  latter  after  using  the  closet,  they  will 
be  rendered  inodorous  and  inoffensive.  For  this  purpose 
loam  and  clay  are  best,  though  sifted  ashes  may  be  used 
with  almost  as  good  results,  but  sand  or  gravel  will  not 
be  as  efficient  as  the  loam  or  ashes.  Moreover,  owing 
probably  to  the  action  of  the  nitrifying  bacteria  in  the 
earth,  all  traces  of  the  peculiar  nature  of  the  organic 
compounds  are  quickly  destroyed,  and  the  mixture  soon 
becomes  practically  nothing  but  humus  and  is  an  excel- 
lent fertilizer. 


PAIL  OR  EARTH-CLOSET  SYSTEM  393 

Harrington^  says  of  peat  used  for  this  purpose  that  it 
"has  not  only  remarkable  power  of  absorption,  but  also 
very  marked  bactericidal  properties.  It  will  absorb  and 
retain  from  nine  to  eighteen  times  its  weight  of  water,  it 
acts  as  a  deodorant  in  the  same  manner  as  charcoal,  and 
it  retains  ammonia  in  apparently  unchanged  condition. 
Experiment  has  shown  that  neither  the  typhoid  nor  cholera 
organisms  can  retain  their  vitality  in  contact  with  peat 
longer  than  a  very  few  hours,  and  the  same  is  true  of 
many  other  varieties  of  bacteria." 

The  pail  or  earth-closet  must,  of  course,  be  separate 
and  apart  from  the  dwelling,  as  it  is  impossible  to  have 
the  same  means  of  keeping  the  gaseous  emanations  and 
effluvia  out  of  the  house  as  with  the  water-carriage 
system;  and  it  is  also  important  that  the  liquid  house- 
slops,  wash-water,  etc.,  be  kept  separate  from  the  fecal 
waste,  which  should  be  kept  as  dry  as  possible  to  lessen 
putrefaction  and  to  increase  its  possible  value  as  a  fer- 
tilizer. Nor  should  this  liquid  waste  be  allowed  to  soak 
into  and  pollute  the  soil  about  the  house.  It  should 
be  collected  in  a  water-tight  reservoir,  whence  it  can  be 
removed  at  frequent  intervals,  or,  better  yet,  carried  by 
suitable  drains  to  a  kitchen  garden  or  other  land  at  a 
proper  distance  from  the  house,  and  be  there  disposed  of 
by  irrigation  or  sub-irrigation. 

As  one  can  readily  see,  the  pail  or  earth-closet  system 
is  especially  well  adapted  to  isolated  houses  and  small 
communities,  where  each  householder  can  take  care  that 
the  necessary  details  are  properly  attended  to,  and  where, 
as  is  likely,  there  is  not  a  general  water-supply,  or  where 
the  expense  of  constructing  the  necessary  sewers  would 
be  too  great. 

But  even  in  cities  as  large  as  Manchester,  England, 
"where  four-fifths  of  the  people  are  obliged  to  have 
earth-closets,"  the  system  is  said  to  have  proved  entirely 
advantageous  and  practicable. 

^  Practical  Hygiene,  1st  edition,  p.  470. 


394     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

Where  there  is  a  common  and  general  supply  of  water 
throughout  the  house  or  to  a  number  of  houses  there  must 
be  some  provision  for  carrying  off  the  waste-water,  and 
as  this  latter  will  probably  have  become  polluted  in  its 
use,  it  will  be  advantageous  to  employ  it  to  remove  the 
other  sewage.  In  fact,  where  the  conditions  are  favorable 
the  water-carriage  system  will  usually  be  found  the  best 
of  all,  because  it  is  more  'nearly  automatic  and  depends 
least  on  human  interference  and  efficiency. 

The  necessary  apparatus  comprises,  on  the  one  hand, 
that  which  belongs  to  the  building  and  its  premises,  viz. : 
the  house  fixtures,  pipes,  and  drains;  and,  on  the  other, 
the  common  or  public  sewers  which  receive  the  sewage 
from  the  house-drains  and  convey  it  to  its  place  of  ulti- 
mate disposal. 

SEWAGE-PLUMBING  AND  HOUSE-DRAINAGE. 

The  essence  of  any  good  system  for  the  removal  of 
sewage  from  a  dwelling  or  building  is  simplicity.  There- 
fore, inasmuch  as  it  has  been  stated  that  sewage  should 
always  be  removed  from  the  premises  as  soon  as  possible 
after  its  production  and  before  fermentation  or  putrefac- 
tion begins  in  it,  it  is  evident  that  in  such  a  system  we 
should  have  for  our  object  and  should  provide  for:  ''(1) 
The  speediest  possible  removal  from  the  house  to  the 
public  sewer  of  excretal  and  other  refuse  by  means  of 
water.  (2)  The  prevention  of  the  deposit  of  foul  matter 
in  any  part  of  the  drainage  system  and  of  percolation  into 
the  soil  of  polluting  liquids.  (3)  The  establishment  of  a 
current  of  air  through  every  part  of  the  soil-drains  and 
pipes,  in  order  to  disperse  any  foul  gases  that  may  form 
and  to  allow  them  to  escape  with  safety  into  the  open  air. 
(4)  The  prevention  of  any  entry  of  air  from  soil-pipes, 
drains,  and  waste-pipes  into  the  house.  (5)  The  exclusion 
of  the  air  of  the  common  sewer  from  the  house-drains 
and  the  house;  the  last  being,  perhaps,  the  most  impor- 
tant, as  the  air  of  the  public  sewer  may  at  any  time  con- 


SEWAGE-PLUMBING  AND  HOUSE-DRAINAGE     395 

tain  the  active  germs  of  specific  disease."^  Some  modern 
authorities,  however,  would  omit  this  last  requirement 
on  the  ground  that  the  air  of  the  street  sewer  is  no  worse 
than  that  in  the  house-drains  and  soil-pipes  of  dwellings 
and  that  the  latter,  because  of  their  number  and  frequency, 
afford  one  of  the  best  means  of  ventilating  the  common 
sewer. 

The  attainment  of  the  above  requirements  is  to  be 
secured  in  the  manner  to  be  described.  The  soil-pipe  is 
that  which  receives  the  sewage  from  water-closets  and, 
usually,  from  the  waste-pipes  of  other  fixtures,  such  as 
bath-tubs,  wash-stands,  sinks,  etc.,  and  which  connects 
them  with  the  house-drain;  the  latter  is  the  conduit 
connecting  the  soil-pipe  with  the  sewer.  Waste-pipes 
convey  the  contents  of  wash-stands  and  other  fixtures  to 
the  soil-pipes  or  to  a  branch  of  the  house-drain.  (See 
Fig.  93.) 

The  soil-pipe  is  usually  located  almost  entirely  within 
the  house,  although,  were  it  not  for  the  danger  of  its  con- 
tents freezing,  it  would  be  better  to  have  it  fastened  to 
the  wall  outside.  It  is  made  of  cast  or  wrought  iron, 
should  be  at  least  four  inches  in  diameter,  should  convey 
the  sewage  as  directly  as  possible  from  the  fixtures  to  the 
house-drain,  and  must  extend  unobstructed  from  the  latter 
to  several  feet  above  the  roof,  ending  where  winds  and 
currents  from  high  walls  and  chimneys  will  not  interfere 
with  its  free  ventilation.  Every  branch  of  the  soil-pipe 
more  than  eight  feet  in  length,  or  to  which  two  or  more 
water-closets  are  connected,  should  also  be  extended  above 
the  roof,  or  else  be  extended  and  connected  to  the  main 
soil-pipe  above  the  highest  fixture  connected  therewith, 
as  there  must  be  no  closed  ends  wherein  foul  or  stagnant 
air  may  collect.  All  joints  must  be  absolutely  air-tight, 
and  the  pipe  must  be  so  secured  that  any  vibration  or 
settling  of  the  building  will  not  be  likely  to  destroy  its 
continuity.   In  new  buildings,  especially,  it  would  be  well  if 

*  L.  C.  Parkes,  Hygiene  and  Public  Health,  2d  edition,  p.  139. 


396     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

all  soil-pipes  were  exposed  or  else  covered  in  with  panels 
easily  removable  at  any"  time  to  permit  of  inspection  or 


MAIN  TRAP 


Fig.  93. — Illustrating  sewage-plumbing  of  a  house.  The  traps  of  the 
rain  leaders  at  their  junctions  with  the  house  drain  have  been  accidentally 
omitted. 


repairs.    Any  hidden  pipes  or  those  difficult  of  access  should 
be  of  extra  heavy  materials,  and  extra  care  should  be  given 


HOUSE-DRAIN 


397 


to  the  joints  and  supports.  The  soil-pipe  and  house-drain 
should  both  be  as  smooth  as  possible  interiorly,  and  in  the 
construction  they  must  be  carefully  inspected  to  prevent 
any  of  the  material  used  in  caulking  or  cementing  the 
joints  from  projecting  within  to  obstruct  the  free  flow 
of  sewage. 

Outside  of  the  house  the  house-drain  may  be  of  iron  or 
of  glazed  and  impervious  earthenware,  but  no  earthen  pipe 
should  be  permitted  within  five  feet  of  a  foundation  wall, 
and  where  any  part  of  the  house- drain  is  within  the  build- 
ing it  should  be  of  iron  and  securely  fastened  to  the 
foundation-wall  above  the  cellar  floor.     The  connection 


Fig.  94. — Method  of  connecting  soil-pipe  with  house-drain. 


between  it  and  any  soil-pipe  should  be  by  means  of 
a  rounded  elbow,  and  not  by  an  abrupt  right  angle. 
(Fig.  94.)  The  house-drain  should  not  be  less  than  four 
nor  more  than  ten  inches  in  diameter,  should  be  laid  on  a 
firm  foundation,  should  have  air-tight  joints,  and  should 
have  a  slope  toward  the  sewer  of  at  least  one-half  inch  to 
the  foot. 

If  a  house-drain  empty  into  a  sewer  of  the  "combined" 
system,  there  should  be  a  trap  just  before  its  junction 
with  the  sewer  to  .prevent  the  passage  of  sewer-air  back 
into  the  house  (Fig.  93)  unless  it  is  planned  to  use  such 


398      THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

house  connections  to  ventilate  the  sewer,  and  there  must 
also  be  an  opening  for  fresh  air  between  this  trap  and 
the  house-drain,  so  that  there  may  be  a  constant  current 
through  the  house-drain  and  soil-pipes  to  the  exit  above 
the  roof,  and  the  air  in  the  soil-pipes  thus  kept  from 
becoming  foul  and  stagnant.  But  if  the  house-drain 
empties  into  a  sewer  of  the  "separate"  system,  there 
need  be  no  trap  between  the  drain  and  sewer,  because 
the  air  in  the  latter  will  probably  be  better  than  that  in 
a  "combined"  sewer  and  because  there  is  otherwise 
practically  no  adequate  ventilation  of  the  "separate" 
sewer.  However,  the  fresh-air  inlet  between  sewer  and 
house-drain  is  always  advisable,  as  it  tends  further  to 
assist  ventilation. 

A  hduse-drain  should  not  empty  into  a  cesspool  unless 
it  is  absolutely  necessary,  and  in  such  case  the  cesspool 
must  be  well  ventilated  and  also  separated  from  the  drain 
by  a  fresh-air  inlet  and  trap,  just  as  when  the  drain 
empties  into  a  combined  sewer.^  Nor  should  any  cess- 
pool empty  into  a  sewer. 

Where  rain-water  conductors  empty  into  house-drains 
or  sewers,  they  should  be  separated  from  the  latter  by 
traps  having  a  seal  of  not  less  than  five  inches,  to  prevent 
sewer-air  passing  up  through  them  to  the  vicinity  of 
windows,  etc.  So,  also,  all  waste-pipes,  gutters,  and  other 
pipes  opening  into  house-drains  should  be  trapped. 

In  the  house  all  water-closets  and  other  fixtures  should 
be  as  near  the  soil-pipe  as  possible  that  there  may  be  no 
long  stretches  of  foul  waste-pipe  underneath  the  floors, 
and  all  connections  with  the  soil-pipe  should  be  made  at 
an  acute  angle  that  the  discharge  into  the  latter  may  not 
interfere  with  its  free  ventilation.  Each  fixture  must  be 
separately  trapped,  and  the  trap  must  be  located  as  near 
its  fixture  as  possible.     There  must  be  no  connection 

^  The  "septic  tank"  hereafter  described  must  not  be  confused  with  the 
cesspool  mentioned  here,  as  it  is  permissible  to  connect  the  house-drain 
directly  to  a  properly  constructed  septic  tank,  for  reasons  that  are  made 
apparent  in  the  description  of  the  latter. 


SEWAGE-TRAPS 


399 


between  a  fixture  and  the  soil-pipe  or  house-drain  which  is 
not  trapped. 

A  little  reflection  will  show  that  by  observing  the  above 
rules  of  construction  provision  will  have  been  made  for 
each  of  the  five  specified  requirements  of  the  system,  and 
the  air  in  the  soil-pipes  will  be  almost  as  pure  as  that  of 
the  house  itself.  The  absorption  of  foul  gases  by  the 
water  in  the  house-traps  and  their  subsequent  dispersion 
into  the  atmosphere  of  the  house  will  also  be  almost 
impossible.  But  there  must  always  be  free  communica- 
tion between  the  air  inlet  into  the  house-drain  and  the 
outlets  from  and  at  the  top  of  the  soil-pipes;  otherwise 


Figs.  95  and  96. — These  illustrations  show  how  a  uniform  caliber 
prevents  the  accumulation  of  dirt  in  a  trap,  and  how  angles  and  corners 
favor  such  accumulations.    (Gerhard.) 


the  air  in  the  soil-pipe  cannot  be  changed  and  foul  gases 
will  accumulate  which,  by  their  pressure,  would  tend  to 
force  themselves  into  the  house  whenever  an  opportunity 
occurred,  and  might  even  overcome  the  seal  of  some  of 
the  traps. 

Sewage-traps  are  "appliances  placed  between  house 
conveniences  (fixtures)  and  soil-pipes  and  drains  or 
sewers,  to  prevent  sewer-gas  gaining  an  entrance  into  the 
house.'*  Many  traps  are  too  complicated.  The  simpler  a 
trap  the  better,  provided  it  have  sufficient  seal.  The  seal 
of  a  trap  is  the  depth  of  water  or  the  mechanical  appliance 
which  prevents  the  back-flow  of  gas.  Mechanical  appli- 
ances are  liable  to  become  clogged  and  not  to  fit  tightly, 


400     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

thus  allowing  the  passage  of  sewer-air;  they  also  tend  to 
check  the  free  onward  flow  of  the  sewage,  thus  favoring 
deposition  in,  and  preventing,  the  cleansing  of  the  trap. 
The  S  or  siphon  trap  is  as  simple  as  any,  is  of  uniform 


Fig.  97. — S  or  siphon  trap,  with 
opening  for  ventilation  pipe. 
(Gerhard.) 


Fig.  98.— Bell  trap. 
(Gerhard.) 


diameter  throughout,  has  no  corners  or  projections  to 
catch  dirt,  and  is  thoroughly  cleansed  by  each  fair  flow 
of  water  through  it.  The  value  of  a  trap  does  not  depend 
so  much  on  the  amount  of  water  it  contains  as  on  the 
depth  or  strength  of  the  seal.    On  account  of  evaporation 


Fig.  99. — Cudell's  trap. 
(Gerhard.) 


Fig.   100. — Bower's  trap. 
(Gerhard.) 


the  water-seal  of  a  trap  may  become  lessened  or  destroyed 
unless  the  fixture  to  which  it  is  attached  be  in  frequent 
use;  it  is  therefore  advisable  to  have  as  few  fixtures  of 
any  kind  in  the  house  as  the  comfort  or  convenience  of 


PREVENTION  OF  SIPHONAGE 


401 


the  inmates  will  allow.  So,  also,  if  a  house  is  to  be  un- 
occupied for  a  time,  it  is  well  to  cover  the  water  in  the 
traps  with  oil  or  glycerin  to  prevent  evaporation  of  the 
former.  Leakage  or  capillary  action,  the  latter  caused 
by  accumulations  of  hair,  thread,  etc.,  in  the  trap,  may 
likewise  lower  the  water  so  that  sewer-gas  may  pass 
through  from  the  soil-pipe. 


Fig.  101. — Grease  trap.     C,  cover;  7,  inlet;  V,  vent:  0,  outlet. 
(Harrington.) 


Lastly,  the  seal  of  a  trap  may  be  broken  by  siphonage, 
either  by  a  strong  rush  of  water  through  it  from  its  own 
fixture,  or  by  a  rush  down  the  soil-pipe  from  a  fixture 
higher  up,  and  this  is  especially  liable  to  occur  if  the  trap 
be  some  distance  from  the  soil-pipe,  or  if  the  fixtures  above 
discharge  a  large  amount  of  water  at  once.  To  prevent 
this,  openings  are  frequently  made  at  the  top  of  the  traps 
on  the  side  next  the  waste-pipe  or  soil-pipe  and  con- 
nected with  vent-pipes,  which  should  open  into  the  soil- 
pipe  above  the  entrance  of  the  waste-pipe  from  the  highest 
fixture,  or  be  continued  separately  into  the  out-door  air. 
(See  Fig.  lOL)  But  this  increases  the  expense,  and,  as 
26 


402    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

the  vent-pipes,  to  be  efficient,  must  be  almost  two  inches 
in  diameter,  they  also  favor  evaporation  from  the  trap. 
If  the  trap  is  properly  constructed,  if  the  soil-pipe  is  of 
suitable  size  and  height,  and  if  the  fixtures  be  placed 
as  near  the  soil-pipe  as  possible,  there  will  be  much  less 
danger  of  siphonage  occurring.  Where  it  does  occur, 
McClellan's  anti-siphon  attachment  (Fig.  102)  is  said  to 
work  advantageously,  being  inexpensive  and  permitting 


Fig.  102. — McClellan's  anti-siphon  attachment.  Sectional  view  of 
vent  with  cup  lifted  out  of  the  mercury  by  the  inflowing  current  of  air, 
indicated  by  the  arrows.     (Rohe.) 


a  free  ingress  of  air  to  the  trap,  but  no  egress  of  air  from 
the  soil-pipe  into  the  house.  In  this  device  a  small 
weighted  and  inverted  cup  rests  with  its  edge  immersed 
in  a  ring  of  mercury,  from  which  it  is  raised  by  the 
atmospheric  pressure  only  when  the  siphonage  sufficiently 
reduces  the  pressure  within  the  pipes.  The  mercury  and 
the  weight  of  the  cup  make  a  seal  sufficient  to  prevent 
any  outflow  of  gas,     It  is  also  said  that  if  the  waste- 


TESTING  OF  PIPES  AND  DRAINS  403 

pipe  be  connected  with  the  soil-pipe  by  a  divergent  open- 
ing, siphonage  will  be  less  likely  to  occur. 


Fig.  103.— a  modern  bath-room.     (Courtesy  of  the  Standard  Sanitary 
Manufacturing  Co.) 

All  waste-pipes,  soil-pipes,  and  house-drains,  should  be 
tested  before  use  by  closing  all  openings  and  forcing  in 
air  to  a  pressure  of  at  least  thirty  pounds  to  the  square 
inch.  Leaks  may  also  be  detected  by  plugging  the  lower 
openings  and  filling  the  pipes  with  water,  or  by  pouring 
an  ounce  of  oil  of  peppermint  into  the  highest  fixture  and 


404    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

quickly  following  this  with  several  gallons  of  hot  water, 
the  heat  volatilizing  the  oil,  whose  odor  escapes  at  every 
opening  in  the  pipes  unprotected  by  a  trap  or  water-seal. 


Fig.  104. — Old-fashioned  wash-basin    with  overflow    horn  discharging 
beneath  plug.     (Harrington.) 


FiQ.  105. — Improved  stand-pipe  overflow.    (Harrington.) 


WATER-CLOSETS  405 

The  heat  imparted  by  the  hot  water  will  also  help  to  trace 
out  hidden  soil-pipes. 

All  fixtures  should  be  exposed  to  the  free  ventilation 
of  air  underneath  and  about  them,  and  water-closets  and 
wash-stands  should  not  be  closed  in  with  carpentry  work. 
(See  Fig.  103.)  Traps  should  also,  if  possible,  be  where 
they  may  be  opened  and  inspected  at  any  time.  Under 
each  closed-in  fixture,  if  there  must  be  such,  there  should 
be  a  drip-safe  to  catch  any  leakage  or  overflow  of  water, 
but  the  pipes,  if  any,  leading  from  these  should  never 
empty  into  waste-pipes  or  soil-pipes;  they  should  lead 
preferably  into  the  open  air  and  not  to  the  cellar,  as 
the  cellar-air,  which  is  usually  impure,  thus  gains  access 
to  the  house.  Even  if  these  drip-safe  pipes  are  trapped 
and  open  into  the  soil-pipe,  ,the  water  in  the  trap  is 
replenished  so  rarely  that  evaporation  soon  destroys  the 
seal  and  allows  the  air  tb  pass  from  the  soil-pipe  into 
the  house. 

The  overflow  pipe  of  old-fashioned  wash-stands  and 
bath-tubs  is  objectionable,  as  it  collects  dirt  of  all  kinds, 
soap,  epithelium,  etc.,  and  it  is  almost  impossible  to  clean 
it.  Beside,  it  will  often  be  found  opening  into  the  waste- 
pipe  below  the  trap,  thus  allowing  the  free  passage  of 
sewer-air  into  the  room.  When  new  fixtures  are  being 
put  in  they  should  preferably  be  such  as  make  use  of  the 
stand-pipe  or  equally  safe  principle  in  the  stoppers  and 
that  have  no  separate  or  concealed  overflow  pipe  or  outlet 
(Figs.  104  and  105). 

Water-closets. — ^The  requisites  for  a  good  water-closet 
are :  that  it  does  not  allow  the  escape  of  sewer-air  from  the 
soil-pipes  into  the  house;  that  it  is  thoroughly  and  easily 
cleaned  each  time  after  use;  that  there  are  no  hidden 
parts  in  which  filth  can  collect,  or  which  cannot  be  readily 
cleaned ;  that  the  flushing  or  washing  out  of  the  closet  be 
done  in  such  a  way  that  dirt  or  spray,  be  not  thrown  into 
the  air  of  the  room ;  that  there  be  sufficient  water-supply 
to  wash  out  the  bowl  and  trap  each  time  and  to  refill  them 
to  the  proper  level;  that  the  trap  itself  is  not  siphoned  or 


406    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

left  empty  by  a  discharge  of  water  from  this  or  another 
fixture. 

Of  the  different  kinds  of  water-closets  the  pan  and  the 
valve  closets  are  among  the  oldest  and  the  worst,  and  should 


1  ',^ff»*ftftfff^r^fTff\ 


/iffHTfiriimTrh" 


Fig.  106.— Pan  closet.     (Gerhard.) 


Fig.  107.— Valve  closet.     (Gerhard.) 


not  be  used  anywhere.  They  consist  of  a  receiving  bowl, 
the  bottom  of  which  opens  into  a  swinging  pan  or  is  closed  by 
a  valve .    The  pan  or  valve  and  the  lower  part  of  the  receiving 


WATER-CLOSETS 


407 


bowl  are  enclosed  in  another  bowl,  the  container,  connected 
with  the  soil-pipe  and  trap.  The  depth  of  water  in  the 
receiving  bowl  in  pan  closets  is  regulated  by  the  depth  of 
the  pan,  and  in  valve  closets  by  the  location  of  an  overflow 
outlet.  In  both  kinds  the  contents  of  the  receiving  bowl 
are  discharged  into  the  container  by  the  tipping  of  the 
pan  or  valve,  and  consequently  the  sides  of  the  con- 
tainer, as  well  as  the  under  side  of  the  pan  or  valve,  soon 
become  thickly  coated  with  filth.  This,  being  hidden, 
accumulates,  decomposes,  and  contaminates  the  air  in  the 


Fig.  108. — Plug  or  plunger  closet,     (Gerhard.) 

container,  which  air  is  of  necessity  discharged  into  the 
room  as  often  as  it  is  displaced  by  the  contents  of  the 
receiving  bowl.  In  valve  closets  the  overflow-pipe  from 
the  receiver  furnishes  an  additional  way  by  which  the 
foul  air  may  pass  from  the  container  into  the  atmosphere 
of  the  room.  It  needs  no  argument  to  show  that  these 
closets  are  decidedly  dangerous  to  health. 

Plug  or  plunger  closets  are  those  in  which  the  outlet 
above  the  trap  is  stoppered  by  a  plunger,  this  being  usu- 
ally in  a  chamber  at  the  side  of  the  receiving  bowl,  and 
are  almost    as  objectionable    as  pan   or  valve  closets, 


408     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

modern  plumbing  wisely  discarding  all  three.  The 
bowl  and  side  chamber  holding  a  considerable  quantity  of 
water,  the  trap  is  well  flushed  out  each  time  of  use;  but 
the  side  chamber  and  plunger,  being  hidden  and  not  easily 
cleaned,  soon  become  coated  with  filth  and  dangerous  to 
health,  as  there  is  nothing  to  prevent  the  air  from  passing 
from'  this  chamber  into  the  room.  Moreover,  the  plug 
may  not  close  the  opening  completely,  thus  allowing  a 
continual  waste  of  water.  A  trapped  overflow-pipe  in 
the  plunger  keeps  the  closet  from  overflowing. 


^MM'A^*i^<.bi^ii^^^Sm 


Fig.  109. — Short-hopper  closet.     (Gerhard.) 

Hopper  closets  consist  simply  of  a  bowl  connected  below 
with  an  ordinary  trap,  and,  as  there  is  nothing  to  get  out 
of  order,  this  kind  is  theoretically  one  of  the  best.  The 
objection  to  long  hoppers  is  that  dirt  is  apt  to  stick  to  the 
sides  and  become  offensive,  but  this  can  be  prevented  if  it 
is  so  arranged  that  water  begins  to  flow  down  the  sides  as 
soon  as  the  closet  is  put  to  use,  thus  preventing  adhesion. 
Short  hoppers  have  not  this  objection,  as  the  feces  fall 
directly  into  the  water  in  the  bowl  and  are  carried  out 
through  the  traps  as  the  bowl  is  flushed.  All  water-closets 
should  have  a  flushing  rim  encircling  the  top,  so  that  all 
sides  of  the  bowel  may  be  washed  down  and  cleansed  each 
time  the  closet  is  used. 

Wash-out  closets  retain  considerable  water  in  the  bowl, 
and  are  emptied  by  a  strong  flush  of  water  from  the 


WATER-CLOSETS 


409 


flushing  rim.  They  are  simple,  do  not  readily  get  out  of 
order,  and  have  been  much  in  favor  up  to  the  present 
time,  but  siphon  closets  are   now  tending  to   supplant 


Fig.  110. — Wash-out  water- 
closet.  (Parkes.)  This  bowl  is 
too  shallow. 


Fig.    111. — Dececo  siphon  closet. 
(Parkes.) 


them.  As  they  are  a  modification  of  the  short-hopper 
closet,  so  is  the  siphon  closet  a  modification  of  the 
wash-out  varietv. 


Fig.  1 12. — Sanitas  siphon  closet.    (Harrington.) 


In  the  siphon  closet  the  contents  of  the  bowl  and  trap 
are  lifted  out  by  siphonic  action,  and  then  the  bowl  and 
trap  are  refilled,  as  in  the  case  of  wash-out  closets,  by  an 
after-flush.  In  the  Dececo  closet — a  siphon  closet — use 
is  made  of  the  principle  involved  in  the  Field  flush-tank. 


410     TttE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

Hopper,  wash-out,  and  siphon  closets  should  be  sup- 
plied from  water-closet  tanks,  which  should  give  a  cer- 
tain and  sufficient  volume  of  water  with  only  a  short  pull 
on  the  chain  or  pressure  on  the  rod  or  knob.  The  bowl 
and  trap  should  also  be  automatically  refilled  from  the 
tank  after  use. 

Water-closets  should  not  be  connected  directly  with  the 
water-supply  pipes  of  the  house,  as  air  from  the  closets 
may  be  sucked  into  them  at  times  when  the  water-supply 
is  cut  off,  and  the  water  afterward  contaminated  by  it. 
But  this  is  difficult  to  avoid  in  pan,  valve,  or  plug  closets, 
and  is  another  serious  objection  to  their  use. 

Vent-pipes  from  the  bowl  and  seat  of  water-closets 
must  be  large,  and  must  not  open  into  the  soil-pipe,  but 
into  the  open-air;  they  must  not  open  near  a  window  nor 
any  place  from  which  air  is  taken  into  the  house,  but  may 
open  into  a  flue  which  is  constantly  heated,  as  a  kitchen 
chimney,  or  may  themselves  be  heated  and  have  a  current 
maintained  in  them  by  a  small  lamp  or  gas-jet.  In  this 
way  the  room  in  which  a  water-closet  is  located  may  be 
effectively  ventilated. 

Water-closets  should  never  be  placed  in  dark  closets 
nor  in  bed-rooms  or  living-rooms,  but  should  always  be 
in  separate  rooms  that  have  free  communication  with  the 
open  air  by  means  of  a  large  window  or  by  a  ventilating 
shaft  of  at  least  four  square  feet  sectional  area  throughout 
its  length.  It  is  also  advisable  that  bed-rooms  should 
not  communicate  directly  with  bath-rooms,  etc.,  con- 
taining water-closets,  unless  there  is  every  assurance  that 
the  closet  and  plumbing  connected  with  it  are  first-class 
in  every  particular. 

It  will  not  be  out  of  place  to  suggest  in  this  connection 
that  apparatus  for  household  conveniences,  such  as  wash- 
stands,  bath-tubs,  water-closets,  kitchen  sinks,  etc.,  which 
satisfies  every  practical  sanitary  requirement  can  now  be 
had  at  prices  that  are  quite  reasonable  when  the  necessary 
care  and  scientific  experience  in  construction  are  taken 
into  consideration.    Much  advance  has  been  in  the  reduc- 


SEWERS  411 

ing  of  the  number  of  parts  in  an  article,  some  being  now 
made  in  a  single  piece,  thus  lessening  or  eliminating  the 
crevices  that  would  collect  and  hold  dangerous  filth; 
likewise  concealed  overflow  pipes  and  corners  and  de- 
pressions difficult  to  clean  have  been  done  away  with; 
and  a  third  gain  has  been  in  the  substitution  of  solid 
vitrified  or  enameled  metal  ware  for  articles  that  were 
made  of  comparatively  soft  substance  and  with  a  glazed 
surface  that  was  liable  to  crack  and  thus  permit  the 
absorption  of  foul  matters  and  possibly  harmful  organ- 
isms. That  these  advantages  have  also  been  accom- 
panied by  an  advance  in  esthetic  appearances  is  well 
demonstrated  by  the  illustration  on  page  93,  or  by 
what  may  be  seen  in  almost  any  well-equipped  modern 
dwelling. 

SEWERS. 

These  are  the  conduits  provided  to  receive  and  convey 
the  contents  of  house-drains  and  other  drains  to  the  place 
of  final  disposal  or  discharge.  They  may  be  of  either  of 
two  kinds — combined  or  separate.  Sewers  of  the  first 
class,  which  have  heretofore  been  most  commonly  used 
in  this  country,  are  constructed  to  carry  off  all  kinds  of 
sewage,  the  waste  liquids,  etc.,  from  factories,  street- 
washings,  and  the  surplus  rain-water  of  the  district 
drained  by  them.  As  this  necessitates  a  size  and  capacity 
sufficient  to  receive  the  greatest  probable  rainfall  upon 
the  area  drained  in  addition  to  the  other  sewage,  it  is 
evident  that  the  depth  of  the  usual  daily  volume  of  the 
latter  in  the  sewer  will  be  so  shallow  and  the  current  so 
sluggish  as  greatly  to  favor  the  settling  of  the  solid  and 
semisolid  constituents,  the  obstruction  of  the  sewers, 
and  the  development  of  bacteria  and  sewer-gas.  To 
obviate  these  faults  and  to  insure  a  more  rapid  flow  by 
keeping  the  depth  of  sewage  as  great  as  possible,  the 
smaller  conduits,  at  least,  are  generally  made  ovoid  in 
section,  the  smaller  end,  of  course,  being  downward. 
Combined  sewers  are  not  only  more  expensive  to  construct 


412    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 


and  to  keep  in  repair  than  those  of  the  separate  system, 
but  greater  care  must  be  had  to  see  that  they  are  at  all 
times  properly  ventilated.  The  main  advantage  claimed 
for  them  is  that  the  expense  of  constructing  separate 
conduits  for  factory  wastes,  street-washings,  and  the 
excess  of  rain-water  is  avoided;  but  this  is  a  doubtful 
one  both  in  respect  to  economy  and  sanitation. 


Fig.  113. — Section  of  ovoid  sewer  of  "combined"  system. 

The  ventilation  of  sewers  of  this  kind  is  usually  suffi- 
ciently provided  for  by  the  inlets  for  street-washings  and 
rain-water  located  at  street-corners,  and  by  manholes  but 
if  these  are  not  close  enough  together  to  keep  the  sewer 
atmosphere  constantly  changing  and  reasonably  pure, 
other  ventilation  openings  should  be  made.  Heretofore 
the  practice  has  been  to  exclude  the  air  of  combined 
sewers  from  house  connections  by  means  of  the  traps 


SEWERS  413 

already  described,  but  of  late  there  is  a  tendency  to 
utilize  such  house  connections  as  efficient  ventilators 
of  the  sewers  because  of  their  number  and  frequency, 
also  because  it  is  realized  that  the  air  of  a  properly  con- 
structed and  maintained  sewer  is  quite  as  pure  as  that 
in  the  house  connection. 

Only  the  sewage  proper  from  dwellings,  and  occasionally 
from  small  factories,  is  admitted  to  the  sewers  of  the 
separate  system,  the  rain-waters,  surface-waters  and  soil- 
waters  being  removed  by  other  drains  or  channels.  The 
advantages  of  this  system,  which  is  now  indorsed  by 
almost  all  sanitarians,  are  that  the  volume  of  sewage  to 
be  carried  is  comparatively  small  and  constant,  and  that 
it  can  be  calculated  very  approximately  from  the  daily 
water-supply  and  population;  that  the  cost  of  construc- 
tion is  much  less  than  that  of  sewers  of  the  combined 
system,  and  that,  while  it  is  available  and  satisfactory 
for  large  cities,  it  is  the  only  one  that  small  communities 
would  consider  or  can  afford;  that  the  sewage  is  more 
concentrated  and  uniform  in  composition,  and  can  thus 
be  better  utilized  as  a  fertilizer  or  disposed  of  in  whatever 
manner  may  be  most  sanitary  and  advantageous;  that  the 
sewers,  having  smaller  peripheries  and  smoother  walls,  are 
more  frequently  and  effectually  flushed,  and  that  they  are 
more  completely  ventilated  and  altogether  better  suited  to 
the  work  to  be  performed.  The  disadvantages  of  sewers 
of  this  class  are  that  a  community  must  have  two  sets  of 
drains,  one  for  sewage  and  the  other  for  rain,  street,  and 
factory  waters,  and  that  after  a  protracted  dry  season  the 
street-washings,  etc.,  may  be  very  foul;  but  these  are  out- 
weighed by  the  advantages  mentioned  above. 

"No  sewer  of  this  system  should  be  more  than  six 
inches  in  diameter  until  it  and  its  branches  have  accumu- 
lated a  sufficient  flow  at  the  hour  of  greatest  use  to  fill 
this  size  half-full,  because  the  use  of  a  larger  size  is  waste- 
ful and  because  ventilation  becomes  less  complete  as  the 
size  increases.  The  size  should  be  increased  gradually 
and  only  so  rapidly  as  is  necessary  by  the  filling  of  the 


414     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

sewer  half-full  at  the  hour  of  greatest  flow;  and  the 
upper  end  of  each  branch  sewer  should  be  provided  with 
an  automatic  flush-tank  (Fig.  114)  of  sufficient  capacity  to 
secure  the  thorough  daily  cleansing  of  so  much  of  the 
conduit  as  from  the  limited  flow  is  liable  to  deposit  solid 
matters  by  the  way." 

There  should  ordinarily  be  no  traps  between  house- 
drains  and  sewers  of  the  separate  system,  since,  having 
no  rain-water  inlets,  the  latter  would  otherwise  have  no 
openings  for  ventilation.  Moreover,  since  the  "separate" 
sewers  are  so  regularly  and  thoroughly  flushed,  the  air  in 


^ 


Fig.  114. — Field's  annular  siphon  flush-tank,     (Parkes.) 

them  is  not  likely  to  be  impure,  and  there  is  not  as 
much  reason  for  excluding  it  from  the  house-drains,  etc., 
as  there  is  regarding  the  air  from  "combined"  sewers. 
The  junction  of  house-drains  with  sewers  of  the  separate 
system  should  be  by  divergent  openings,  so  that  the  air 
may  pass  freely  into  the  drain  as  the  sewage  empties  into 
the  sewer. 

Should  one  desire,  however,  to  separate  his  house-drain 
from  the  public  sewer  by  means  of  a  trap,  and  thus 
prevent  the  ingress  of  sewer-air  into  his  premises,  the 
ventilation  of  the  sewer  can  be  secured  by  providing  a 
vent-pipe  between  the  trap  and  the  sewer.     But  in  no 


DISPOSAL  OF  SEWAGE  415 

case  must  the  inlet-pipe  for  air  on  the  other  side  of  the 
trap,  between  it  and  the  house,  be  omitted;  nor  should 
the  two  air-pipes  be  so  near  together  that  air  from  the 
former  will  be  likely  to  be  drawn  into  the  latter. 

All  sewers  should  be  laid  on  a  good  foundation  with 
sufficient  fall  to  give  at  least  a  velocity  of  two  feet  per 
second  to  the  flow.  If  made  of  brick,  they  should  be 
laid  in  a  mortar  made  of  cement  and  sharp  sand,  and  all 
sewers  should  be  as  smooth  as  possible  inside  to  prevent 
the  arrest  of  particles  of  sewage.  Sewers  of  the  com- 
bined system  shpuld  not  be  pervious  to  the  soil-water,  as 
the  liquid  sewage  is  just  as  apt  to  pass  from  them  to  the 
soil  and  to  pollute  it  dangerously  as  the  soil-water  is  to 
pass  into  the  sewers.  But  the  rain-water  drains  of  the 
separate  system  may  also  be  employed  to  drain  the  subsoil. 


DISPOSAL  OF   SEWAGE. 

The  ultimate  disposal  of  sewage  is  a  matter  of  consider- 
able importance  which  commonly  does  not  receive  the 
attention  it  deserves.  The  method  frequently  employed 
in  this  country  of  discharging  the  sewage  into  a  running 
stream  is  reprehensible,  because  the  natural  purification  of 
a  water  thus  contaminated  must  always  be  slow  and  more 
or  less  uncertain,  and  because  the  risk  to  those  using 
the  polluted  water  must  be  a  constantly  -increasing  one. 
Where  the  district  drained  and  supplied  by  the  stream 
is  a  sparsely  settled  one,  and  where  the  volume  of 
fresh  or  running  water  is  very  large  in  proportion  to  the 
quantity  of  pollution  it  receives,  the  objections  to  the 
disposal  of  sewage  in  this  way  may  seem  to  be  theo- 
retical rather  than  practical;  but  as  the  population  in- 
creases and  the  ratio  of  pure  water  to  filth  decreases 
beyond  certain  limits,  the  question  becomes  more  serious 
and  pertinent.  It  is  said  that  to  dilute  safely  the  sewage 
of  1000  persons  requires  from  2,000,000  to  4,000,000 
gallons  of  unpolluted^ water  per  day;  this,  of  course,  not 


416     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

destroying  the  disease  germs  nor  eliminating  the  danger 
of  their  multiplication. 

Other  methods  of  sewage  disposal  resemble  closely 
those  already  described  for  the  purification  of  water,  in 
that  they  make  use  of  straining  and  subsidence,  chemical 
and  biological  treatment,  and  filtration.  In  order  that 
sewage  may  "lose  permanently  its  power  for  evil"  and 
not  be  a  source  of  nuisance  either  to  the  community  from 
which  it  comes  or  to  others,  it  is  necessary  that  it  undergo 
certain  changes  or  treatment  after  it  reaches  the  end  of  the 
sewer  system  and  before  being  discharged  into  a  stream 
or  body  of  water  which,  perforce,  must  practically  always 
be  the  ultimate  destination  of  the  water  content  (over  99 
per  cent.)  of  all  sewage.  Such  change  or  treatment  con- 
sists essentially  in  the  oxidation  and  mineralization  of 
the  putrescible  organic  constituents  of  the  sewage  into 
the  simplest  end-products,  viz.,  carbonic  and  nitric  acids 
and  their  salts,  and  water;  the  elimination  or  destruction 
of  pathogenic  organisms,  and,  incidentally  or  where 
necessary,  the  removal  of  insoluble  inorganic  matter  or 
of  certain  harmful  or  objectionable  factory  wastes,  acids, 
alkalies,  etc. 

What  method  will  be  best  suited  and  most  satisfactory 
for  a  given  locality  can  only  be  determined  by  a  con- 
sideration of  all  the  conditions  and  factors  involved, 
including  frequently  careful  preliminary  experimental 
treatment  over  a  reasonable  period  of  time.  The  installa- 
tion of  works  for  the  proper  conversion  of  the  sewage  of 
a  community  will  relatively  involve  considerable  expense, 
and  it  will  be  difficult  or  impossible  in  the  near  future 
to  secure  a  change  in  method,  if  a  wrong  or  unsatisfactory 
one  be  first  put  in  use.  Among  the  methods  already 
successfully  employed  both  in  this  country  and  abroad 
may  be  mentioned,  straining  by  means  of  fixed  or  movable 
screens,  sedimentation,  liquefaction  by  so-called  ''septic" 
action,  the  use  of  activated  sludge,  filtration  and  irriga- 
tion. The  striking  feature  is  that  in  almost  all  of  these 
except  sedimentation  and  mechanical  straining,  the  essen- 


PLATE    V 


FACTORS  IN  SEWAGE  PURIFICATION  BY  DILUTION 

MAN 


BACTERIA 


^   ^ 


HAVING  FLAGELLA 


ALGA 


MICRRSTERIAS 


PROTOZOA 


CRUSTACEA 

FISH 


PERIDINIUM 


■^ 


C'-^L.OPS  —  .^^,     ,  NAUPLIU5 


BUREAU    OF    SURVEYS 

DEPARTMENT  OF  PUBUC  WOWCS 

CITY   OF   PHILADELPHIA 

AUGUST  I9l3. 


DISPOSAL  OF  SEWAGE  •        417 

tial  and  greater  part  of  the  work  is  done  by  the  living 
microorganisms  normally  present  in  the  sewage  itself 
and  without  the  addition  of  extraneous  substances.  Two 
or  more  of  the  above  methods  may  be  and  frequently  are 
combined  with  much  better  results  than  would  be  possible 
if  only  one  of  them  were  used. 

Straining  is  accomplished  by  means  of  screens  of  various 
kinds  or  by  coarse-grained  filters  made  of  coke  (one-quarter 
inch),  buckwheat  coal  or  the  like.  The  screens  may  be 
fixed  or  movable  and  be  made  of  rods,  wire  gauze  or 
perforated  plates  with  openings  of  various  sizes  according 
to  the  material  which  it  is  desired  to  remove  by  this 
method  and  also  according  to  the  subsequent  treatment 
of  the  sewage.  The  movable  screens  bring  the  collected 
matter  above  the  surface  of  the  sewage  where  they  are 
cleaned  by  brushes,  scrapers  or  an  air  blast. 

The  simplest  sedimentation  treatment  is  to  allow  the 
sewage  to  flow  slowly  through  a  tank,  this  securing 
better  deposition  of  the  sludge  than  the  alternate  filling, 
and  emptying  of  the  settling  basin,  provided  the  addition 
of  chemical  precipitants  is  not  to  be  madjg.  Care  should 
be  had  to  secure  an  even  flow  through  the  whole  cross- 
section  of  the  tank  above  the  sludge  deposit  on  the  bottom . 
With  a  rate  of  flow  about  fifty  feet  per  hour  and  four  hours 
or  so  for  the  time  of  settling,  good  results  may  be  expected. 

The  sewage  may  be  collected  in  large  tanks,  with  the 
addition  of  certain  chemicals,  such  as  lime,  alum,  or  sulphate 
of  iron,  to  increase  the  precipitation,  and  the  suspended 
impurities  allowed  to  settle  to  the  bottom  of  the  tanks, 
whence  they  can  be  removed,  squeezed  partially  dry  in 
hydraulic  presses,  and  either  disposed  of  as  a  fertilizer  or 
cremated.  The  clear  effluent  or  liquid  part  of  the  sewage 
may  be  allowed  to  flow  at  once  from  the  settling  tanks 
into  a  convenient  watercourse,  provided  it  is  there  well 
diluted,  or  it  may  better  be  filtered  through  an  area  of 
porous  soil  or  through  prepared  filter-beds.  If  the  filtration 
is  properly  done,  the  filtrate  will  contain  nothing  harmful, 
and  may  be  allowed  to  flow  where  it  will  without  danger. 
27 


418     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

Chemical  treatment  will  probably  cost  from  thirty-five 
to  fifty  cents  or  more  per  annum  per  individual  of  the 
population  supplying  the  sewage,  but  an  even  more  im- 
portant question  than  cost  is  whether  the  addition  of  the 
chemicals  may  not  interfere  with  the  natural  biological 
processes  of  purification  constantly  taking  place  in  most 
sewage  and  interfere  with  the  further  purification  of  the 
effluent.  Chemicals  that  are  or  have  been  used  as  pre- 
cipitants  are  lime,  lime  with  sulphate  of  iron,  alum,  or 
alkali  waste,  sulphate  of  iron  alone,  and  a  combination  of 
alum,  charcoal,  and  clay.  The  precipitate  obtained  with 
the  latter  makes  a  fertilizer  of  some  value,  but  it  is  not 
well  to  count  too  much  upon  a  financial  return  from  this 
as  a  by-product. 

The  septic-tank  system  for  the  disposal  of  sewage  par- 
ticularly aims  to  take  advantage  of  the  biological  and 
saprophytic  action  occurring  naturally  in  all  polluted 
waters.  The  idea  is  to  favor  and  not  to  hinder  the  purify- 
ing bacteria  and  other  agencies  by  placing  the  sewage 
under  the  conditions  most  favorable  to  their  growth  and 
action,  thus  facilitating  the  conversion  of  organic  matters, 
both  solid  and  dissolved,  into  substances  entirely  harmless 
and  unobjectionable.  In  other  words,  advantage  is  to  be 
taken  of  the  action  of  both  the  anaerobic  and  aerobic 
saprophytes  which  abound  in  all  sewage  that  is  not  too 
strongly  impregnated  with  antiseptic  chemical  wastes 
from  factories  or  other  sources.  In  the  intermittent 
filtration  and  irrigation  methods  of  sewage  disposal  the 
service  of  the  anaerobic  organisms  is  practically  eliminated 
because  the  success  of  these  methods  depends  largely  upon 
a  free  and  frequent  aeration  of  the  filtering  material  or 
the  soil.  On  the  other  hand,  the  purpose  of  the  septic 
tank  is  first  to  make  use  of  the  disintegrating  and  lique- 
fying action  of  the  anaerobic  bacteria  upon  the  undissolved 
organic  matter  before  subjecting  the  sewage  to  the  action 
of  the  aerobic  bacteria  which  it  contains.  Hence  it  is 
well  to  precede  either  intermittent  filtration  or  irrigation 
by  first  passing  the  sewage  through  the  septic  tank,    A 


THE  SEPTIC  TANK 


419 


similar  action  but  not  so  complete  may  be  had  by  the 
preliminary  use  of  a  contact  filter. 

The  septic  tank  for  large  volumes  of  sewage  should  be 
long  and  comparatively  shallow,  but  should  have  such  a 
capacity  and  cross-section  that  the  sewage  will  pass 
through  the  tank  in  from  six  to  twelve  hours.  At  the 
upper  end  the  fresh  sewage  should  enter  within  a  few 
inches  of  the  bottom  of  the  settling  or  "grit  chamber," 


^ct 


X) 


Caipocy//  320^a/. 


©I 


;;:^:^\:;:/^'::\;;/^^o^v/{v^:X:-.:/•v^<<;V^^•i^y^/^^•cr?^■i;:^y;^iy?gt^: 


ir 


^^^■^l^:\■^-M'^^.^^:^:::^T^^.^:^^^^}>^^:-N^^,,Kl,:r^^^.^^^^ 


:  \' 

.1  ±^ 

0  C 

•1) 


l^i- 


p;. . •.<-,••- 1.-./^< -A*.-,  -.v.-i. 


<?->L 


X 


v/. 

'-0 


lu^^^^^^^^^jy 


c/        f 


///€f  C    '\v% 


Fig.  115. — Double-chamber  septic  tank  for  family  of  six  people,  suitable 
to  conditions  where  outlet  fall  is  difficult  to  obtain.^ 

which  is  separated  by  a  partition  from  the  rest  of  the  tank, 
and  in  which  most  of  the  street  sand  and  other  inorganic 
solids  are  collected.  Thence  it  goes  into  the  larger  space, 
where  the  anaerobic  bacteria  carry  on  their  work. 

The  tank  may  be  entirely  covered  in  to  exclude  air 
and  light,  for  though  a  thick  scum  or  cake  of  sludge  soon 


U.  S.  Bulletin. 


420     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

forms  on  top  that  would  serve  this  purpose,  there  is  some 
possibiHty  of  it  being  broken  and  air  admitted  by  ice, 
snow,  and  other  causes.  However,  experience  has  seemed 
to  show  that  tanks  without  other  covering  than  the 
sludge  work  fairly  well  and  to  give  an  effluent  as  good 
as  that  from  tanks  that  were  covered.  As  the  sewage 
passes  slowly  through  the  tank  the  organic  matter  is 
decomposed  with  the  evolution  of  considerable  gas  that 


DIAGRAM  SHOWING 

TME    CONSTRUCTION  OF  AN 

EM5CMER  TANK 


CITY  Of    PH1LA0EI.DHI4 

OEPARTMCNT  OF  Public  wooks 

BUREAU  OF  SuRVEVS 
SfWAOE     OliPOSAL  DIVISION 


Fig.  116 


might  be  collected  and  used  for  heating  or  lighting 
purposes,  if  the  tank  and  volume  of  sewage  were  large 
enough  to  warrant  it.  An  important  variation  of  the 
septic  tank  is  the  so-called  "digestion  tank.''  Of  these 
"the  best  known  type  is  the  Imhoff,  or  Emscher,  tank. 
This  is  a  deep  septic  tank  divided  by  sloping  partitions 
into  an  upper  and  a  lower  compartment,  so  arranged  that 
the  sewage  flows  slowly  through  the  upper  compartment 
while  the  sludge  settles  through  openings  in  the  partition 


DISPOSAL  OF  EFFLUENT 


421 


walls  into  the  lower  compartment,  where  digestion  takes 
place.  The  advantage  of  this  type  of  septic  tank  is  that 
the  sludge  alone  is  submitted  to  septic  action  without 
allowing  the  products  of  decomposition  to  mix  with 
the  flowing  sewage  above,  while  more  complete  digestion 
improves  the  character  of  the  sludge  from  the  stand-point 
of  subsequent  disposal.^"  This  virtue  of  smaller  bulk  and 
quicker  drying  possessed  by  the  sludge  from  Emscher 
tanks  is  of  considerable  importance  when  the  volume  of 
sewage  to  be  treated  is  as  great  as  that  furnished  by  our 
larger  American  cities  with  their  abundant  water  supplies. 

The  author  just  quoted  also  states  that  septic  sedi- 
mentation continued  from  twenty-four  to  forty-eight 
hours  will  remove  from  40  to  50  per  cent,  of  suspended 
matter  in  weak  sewage  and  from  80  to  85  per  cent,  in 
strong  sew^age. 

The  following  table  prepared  by  Dr.  Rideal  indicates 
the  changes  in  sewage  due  to  biologic  action  in  septic 
tanks,  contact  beds,  trickling  and  intermittent  filters,  etc 


Substances  dealt  with. 

Characteristic  products. 

Initial. 

Transient  aerobic 

Urea,    ammonia,    and 

changes  by  the  oxy- 

easily  decomposable 

gen  of  the  water  sup- 

matters 

/- 

ply,   rapidly  passing 
to: 

First  Stage. 

Anaerobic   liquefaction 

Albuminous     matters; 

Soluble   nitrogenous 

and    preparation    by 

cellulose    and    fiber; 

compounds  and  fatty 

hydrolysis 

fats 

acids;  phenol  deriva- 

Second Stage. 

tives;  gases,  ammonia 

Semi-anaerobic    break- 

Amido   compounds; 

Ammonia,  nitrites, 

ing  down  of  the  inter- 

fatty acids,  dissolved 

gases. 

mediate    dissolved 

residues,    phenolic 

bodies 

bodies 

Third  Stage. 

Complete  atiration;  ni- 

Ammonia  and    carbo- 

Carbonic   acid,    water 

trification 

naceous  residues 

and  nitrates. 

1  Rosenau,  Preventive  Medicine  and  Hygiene,  p.  853. 


422    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

The  effluent  from  a  septic  tank  may  be  carried  into 
a  shallow  aerating  trough  over  the  sides  of  which  the 
fluid  flows  in  thin  sheets,  whence  it  may  be  conveyed 
to  intermittent  filters  or  irrigation  fields;  or  it  may  be 
distributed  through  fixed  or  travelling  sprinklers  on 
aerobic  or  contact  beds,  or  on  trickling  filters,  the  object 
in  all  being  to  enable  the  sewage  to  be  thoroughly  and 
speedily  acted  upon  by  the  aerobic  bacteria.  Irrigation 
fields  for  our  larger  and  rapidly  growing  cities  are  prac- 


FiG.  117. — Trickling  or  percolating  filter,  Pennypack  Creek  Works, 
Philadelphia. 

tically  out  of  the  question  because  of  the  great  area  of 
necessary  land  and  its  high  cost,  and  for  the  same  reason 
intermittent  filters  may  also  be  inadvisable  for  cities  of 
the  largest  size.  For  it  must  be  remembered  that  the 
volume  of  sewage  per  capita  is  very  much  greater  in 
American  than  in  foreign  cities,  both  because  of  our 
overgenerous  supplies  of  water  to  dwellings  and  of  the 
almost  universal  use  of  "combined"  sewers,  which  add 
the  rain-water,  factory  wastes  and  street  washings  to  the 
sewage  proper. 


TRICKLING  OR  PERCOLATING  FILTERS       423 

Aerobic   or   contact   beds   are   large   water-tight   vats 
or  tanks  filled  with  porous  materials,  such  as  cinders  or 
coke,  etc.,  from  i  to  J  inch  in  size,  the  idea  being  that 
there  should  be  as  much  capacity  for  the  sewage  as  possible, 
and  at  the  same  time  a  ready  aeration  of  the  mass  when 
the  bed  is  drained,   the  beds  becoming  more  efficient 
after  being  used  some  time,  as  they  have  thus  become 
impregnated  with  the  right  kinds  of  bacteria.    When  a 
contact  bed  is  filled  with  sewage  and  allowed  to  stand 
there  is  a  rapid  deposit  of  suspended  and  colloidal  matter 
upon  the  myriads  of  surfaces  of  the  solid  material  of 
which  the  filter  is  constructed,  which  deposit  is  rapidly 
acted  upon  by  the  ever  present  bacteria  which  increase  in 
number  from  day  to  day.    This  action  is  partly  anaerobic 
when  the  bed  is  filled  with  sewage,  but  becomes  mainly 
aerobic  as  the  fluid  is  drawTi  off  and  air  refills  the  inter- 
stices of  the  bed.     After  filling,  the  beds  are  left  undis- 
turbed  for  a   couple   of  hours,   and   are   then  drained, 
after  which  they  remain  empty  for  from  two  to  four 
hours,    it  having  been   found   possible   by   using   auto- 
matic filling  and  emptying  valves  to  repeat  the  process 
three  or  four  times  daily.     It  will  usually  be  wise  to 
carry  the  effluent  from  the  septic  tank  through  at  least 
two  of  these  beds,  but  if  the  process  is  properly  accom- 
plished,   "by   this   purification    an   effluent    is   obtained 
which  is  saturated  with  dissolved  oxygen,  which  remains 
entirely  inoffensive  in  smell  for  an  indefinite  period  in  an 
incubator  at  summer  heat,  and  which  therefore,  when  dis- 
charged into  a  water-course,  would  maintain  the  respira- 
tion of  fish,  and  would  never  render  the  water  offensive."^ 
"Trickling  filters,  otherwise  called  'sprinkling  filters' 
or  'percolating  filters,'  consist  of  beds  of  porous  material 
such  as  broken  stone,  coke  or  clinkers  upon  which  the 
sewage  is  sprinkled  and  through  which  it  percolates  to 
underdrains  laid  on  a  tight  floor  beneath.    The  entire  bed 
is  arranged  with  reference  to  complete  aeration  through- 

1  Leffmann,  Civic  Hygiene,  in  Vol.  V  of  Cohen's  System  of  Physio- 
logic Therapeutics. 


424    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

out,  in  order  that  the  organic  matter  of  the  sewage  may  be- 
come thoroughly  oxidized.  The  suspended  matter  of  the 
sewage  is  not  permanently  retained  in  the  beds,  but  flakes 
off  at  intervals  and  is  carried  out  in  the  effluent,  which  is 
turbid  and  requires  subsequent  clarification.  The  object  of 
the  trickling  filter  is  to  change  the  character  of  the  organic 
matter  so  as  to  render  it  non-putrescible.  The  rate  of 
application  varies  from  500,000  to  2,000,000  gallons  per 
acre  daily,  one  acre  of  trickling  filter  serving  a  popula- 
tion of  10,000  or  more.  Well-operated  sprinkling  filters 
receiving  the  effluent  from  plain  sedimentation  or  septic 
tanks  are  capable  of  removing  from  85  to  90  per  cent,  of 
the  suspended  matter  and  from  90  to  95  per  cent,  of 
bacteria,  yielding  an  effluent  that  is  non-putrescible. 
This  method  is  useful  when  sandy  areas  of  suitable  size 
are  not .  available  for  intermittent  filtration  or  are  too 
expensive.^  The  subsequent  clarification  of  the  effluent 
from  trickling  or  sprinkling  filters  may  be  satisfactorily 
accomplished  by  the  addition  of  chlorinated  lime  and 
passage  through  a  settling  basin  of  moderate  size. 

Sewage  may  also  be  disposed  of  by  intermittent  down- 
ward filtration,  either  through  specially  constructed  filter- 
beds  or  a  prepared  area  of  soil  and  by  irrigation  or  sub  irri- 
gation. *'The  volume  of  sewage  which  may  be  success- 
fully purified  upon  a  given  filter  area  is  inversely  propor- 
tional to  the  amount  of  suspended  matters  in  the  sewage 
applied.  In  other  words,  if  the  whole  or  a  part  of  the 
suspended  matters  are  removed  from  the  sewage  by  some 
treatment  preliminary  to  filtration,  the  filters  can  be 
operated  at  much  greater  rates  and  a  smaller  area  will  be 
required  for  the  treatment  of  a  given  volume  of  sewage.^" 

For  sewage,  intermittent  filtration  is  superior  to  the 
continuous  process — in  fact,  is  almost  essential,  as  the 
interruption  in  the  percolation  permits  a  renewal  of  the 
air-supply  in  the  filtering  medium  or  soil,  and  thus  fur- 

1  Rosenau,  Preventive  Medicine  and  Hygiene,  p.  858. 

2  Report  of  Massachusetts  State  Board  of  Health,  1908. 


INTERMITTENT  FILTRATION— IRRIGATION     425 

nishes  a  sufficient  quota  of  oxygen  for  the  use  of  the 
aerobic  bacteria  and  for  the  oxidation  and  nitrification 
of  the  excessive  amount  of  organic  matter  in  the  sew- 
age. With  sufficiently  frequent  intermittence,  fine  sand, 
such  as  is  used  for  building  purposes,  makes  an  excellent 
artificial  filter,  capable,  it  is  stated,  of  purifying  50,000 
gallons  of  crude  sewage  per  acre  per  day  and  of  removing 
all  the  solids,  much  of  the  dissolved  matters,  and  99 
per  cent,  of  the  contained  bacteria.  Where  the  crude 
sewage  is  allowed  to  settle  or  is  treated  biologically  in 
septic  tanks,  a  much  greater  quantity  of  the  clarified 
effluent  can  be  filtered  daily,  as  has  been  indicated. 

By  intermittent  soil  filtration  we  mean  "the  concentra- 
tion of  sewage  at  short  intervals,  on  an  area  of  specially 
chosen  porous  ground,  as  small  as  will  absorb  and  cleanse 
it;  not  excluding  vegetation,  but  making  the  produce  of 
secondary  importance.  The  intermittency  of  application 
is  a  sine  qua  non  even  in  suitably  constituted  soils  where- 
ever  complete  success  is  aimed  at."^  The  land  should  be 
levelled  and  underdrained  with  tile  drains  at  the  depth  of 
five  or  six  feet,  and  should  be  divided  into  four  parts,  no 
part  to  receive  sewage  for  a  longer  time  than  that  which 
comprises  one-quarter  of  the  daily  flow.  An  acre  of 
properly  prepared  soil  wdll  thus  dispose  of  the  crude 
sewage  of  1000  to  2000,  or  the  clarified  sewage  of  5000 
people. 

The  soil  to  be  used  for  this  purpose,  as  well  as  that  for 
irrigation  and  subirrigation,  should  be  porous  and  loamy; 
if  clay,  it  should  be  well  broken  up  and  mixed  with  ashes; 
sand  does  not  purify  sewage  well,  especially  at  first,  in 
these  methods.  The  sewage  impurities  are  removed 
partly  by  mechanical  filtration,  but  especially  by  oxida- 
tion, the  latter  being  due  partly  to  the  air  in  the  interstices 
of  the  soil,  but  chiefly  to  the  aerobic  saprophytic  bacteria, 
which  rapidly  convert  the  organic  impurities  into  ammonia, 
nitrates,  nitrites,  and  other  simple  compounds. 

»  Metropolitan  Sewage  Commission;    see  Notter  and  Firth,  p.  546. 


426    THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

Irrigation  means  ''the  distribution  of  sewage  over  a 
large  surface  of  ordinary  agricultural  ground,  having  in 
view  a  maximum  growth  of  vegetation,  consistently  with 
due  purification,  for  the  amount  of  sewage  supplied."^ 
Subirrigation  is  a  modification  of  this,  the  sewage  being 
delivered  through  uncemented  drains  a  few  inches  beneath 
the  surface  of  the  soil.  Unless  very  porous,  the  land  should 
be  underdrained ;  it  should  also  be  levelled  to  prevent  the 
sewage  flowing  off  the  surface  too  rapidly.  The  under- 
drains  need  not  be  nearly  so  close  together,  however,  as  in 
the  intermittent  filtration  system.  The  crops  raised  on 
irrigation  farms  are  healthful  in  every  respect,  and  there 
can  be  no  reasonable  objection  to  their  use  as  food;  there 
would  be  decided  objection,  however,  to  sprinkling  the 
vegetables  with  sewage  water. 

For  example,  an  epidemic  of  typhoid  fever  in  Prague, 
in  1903,  was  traced  to  the  use  of  radishes  which  had  been 
placed  in  polluted  river  water  in  order  to  freshen  them 
and  improve  their  appearance  for  marketing.  It  is  ac- 
cordingly probable  that  many  cases  of  this  disease  of  ob- 
scure origin  may  arise  in  a  similar  way,  since  it  is  by  no 
means  uncommon  for  the  "truck"  gardeners  in  the  neigh- 
borhood of  cities  to  use  the  contents  of  privy  vaults 
etc.,  as  fertilizer,  and  Rullman  has  shown  that  typhoid 
bacilli  may  live  for  six  months  or  even  a  year  in  human, 
and  more  especially  in  organic  filth.  Thus  celery,  banked 
for  bleaching  with  such  a  soil,  might  readily  become  a 
carrier  of  the  harmful  germs.  On  the  other  hand,  it  is 
not  likely  that  the  latter  are  carried  to  and  taken  up  by 
the  rootlets  of  the  plants  growing  on  the  sewage  farms, 
for  the  records  of  the  latter  thus  far  tend  to  disprove 
this. 

On  the  large  irrigation  farms  of  the  city  of  Berlin,  which 
has  a  population  of  about  two  million,  the  cost  of  sewage 
disposal  before  the  recent  war  w^as  about  covered  by  the 
returns  from  the  crops  raised  upon  them.     The  mortality 

1  Metropolitan  Sewage  Commission;  see  Notter  and  Firth,  p.  547. 


SEPTIC  TANKS  FOR  PRIVATE  DWELLINGS     427 

of  those  employed  upon  them  is  very  low,  and  there  seems 
to  be  no  particular  tendency  to  illness  that  can  be 
attributed  to  the  sewage.  It  is  even  said  that  the 
employees  use  with  impunity  the  clear  water  in  the  effluent 
canals  for  drinking  and  other  purposes.  Paris  has  also 
adopted  the  irrigation  method,  and  the  sewage  of 
the  entire  city  is  treated  in  this  way.  The  sewage  of 
from  100  to  150  persons  per  acre  may  be  satisfactorily 
disposed  of  by  irrigation,  Berlin's  rate,  with  an  especially 
favorable  soil,  being  142  per  acre.  It  is  to  be  especially 
recommended  for  isolated  houses,  for  small  communities, 
or  for  charitable  or  other  State  institutions. 


SURFACE  OF  GROUND 


"fOM 


Fig.  118. — Septic  tank  for  private  dwelling. 


For  private  suburban  or  country  dwellings,  the  Illinois 
State  Board  of  Health  have  recommended  the  small  septic 
tank  illustrated  in  Figs.  118  and  119,  for  which  the  follow- 
ing description  is  given. ^ 

"The  plans  shown  here  are  for  a  tank  suited  to  the  uses 
of  the  ordinary  household  of  from  five  to  ten  persons,  and, 

'  See  Bulletin,  September,  1906,  vol.  ii,  No.  5. 


428     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 


FROM  THE  HOU^^t 


SEWAGE  FI.FUD 


Fig.  119. — Septic  tank  for  private  dwelling. 


C././^ANHOLC 


ON  LCreL    GttOUNO 
use  THtS  OUTLET. 


TOP  l/ZSkV. 
Fig.  120. — Single-chamber  septic  tank  for  six  people.^ 


1  U.  S.  Department  of  Agriculture,  Bulletin  on  Water  Supply,  Plumb- 
ing, and  Sewage  Disposal  for  Country  Homes. 


CONSTRUCTION  OF  SMALL  SEPTIC  TANKS     429 


with  a  fair  amount  of  intelligent  attention,  it  will  ac- 
complish its  purpose  excellently,  removing  from  the  rural 
or  suburban  home  a  factor  which  is  gradually  becoming 
a  distinct  menace  to  the  public  health." 


C  /  M/^NHOL£ 


y^ 


"^ 


C.f.  /^ANHOLS  ^ 

«     a  *1-1.- Z  ~-'Lo    ■  <■■.■■■■».    ,■■■  o    .o  ■  ■«  .  ■«.■»•■  ■■;.»;.■..■«■.■.  .■':4'--»X~-~-~-~-~.t»75rr 


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'A^'  RODS 


wAreR  L/Ner. 


6'6' 


SlOf=>£  SLfCHTLY-  TOWARD  /NLET 


S£TCr/OUAL    v/£y/. 


t'O' 
yVAT^R  LINE 


TOP  V/SIV. 
Fig.  121. — Double-chamber  septic  tank  for  eight  people.* 

"This  plant  consists  of  two  tanks,  the  first  the  septic 
tank  proper,  the  second,  a  discharging  tank.  The  septic 
tank  is,  in  construction,  practically  a  cistern  4  feet  in 
diameter  and  about  3  feet  deep.  The  sewage  from  the 
house  enters  this  tank  through  a  lightly  trapped  pipe,  the 
flow  from  the  ordinary  household  preventing  the  back-flow 
of  air.     Across  the  center  of  the  tank  is  a  wall  which 


1  U.  S.  Department  of  Agriculture,  Bulletin  on  Water  Supply,  Plumb- 
ing, and  Sewage  Disposal  for  Country  Homes. 


430     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

divides  it  into  two  chambers  of  equal  size.  The  height 
of  this  wall  is  exactly  to  the  point  of  outflow. 

"  The  sewage  from  the  house  enters  the  first  chamber  of 
the  septic  tank  with  considerable  force,  causing  some  dis- 
turbance of  the  contents.  The  flow  over  the  dividing 
wall  into  the  second  chamber,  however,  is  even  and  slow, 
so  that  the  contents  of  the  second  chamber  are  not  dis- 
turbed and  the  flocculent  matter  settles  readily  to  the 
bottom. 

"The  bacterial  action  on  the  contents  of  this  tank  is 
often  so  complete  that  there  is  no  appreciable  residue  or 
sludge,  and  in  this  case  the  tank  will  rarely,  if  ever,  have 
to  be  cleaned  out.  In  some  instances,  however,  the  tank 
will  require  occasional  cleaning.  The  sludge  from  a  well- 
constructed  tank  is  not  offensive,  and  may  be  disposed  of 
without  difficulty. 

"The  sewage  is  carried  into  the  discharging  chamber 
(which  is  a  cistern  6  feet  in  diameter  and  about  4  feet  in 
depth),  through  a  deeply  trapped  pipe.  The  second  or 
discharging  tank  should  be  of  sufficient  size  to  hold  the 
overflow  from  the  septic  tank  for  a  period  of  12  to  24 
hours.  At  the  bottom  of  the  discharging  tank  is  an  auto- 
matic siphon  which  is  opened  automatically  when  the 
effluent  reaches  a  certain  height  in  the  tank  or  chamber — 
a  height  of  about  2  J  feet.  Through  this  siphon  the  con- 
tents of  the  chamber  will  pass  in  a  very  few  moments,  at 
which  time  the  siphon  will  automatically  close  and  the 
chamber  will  again  refill. 

"  From  the  siphon  a  pipe  conducts  the  effluent,  which  is 
usually  entirely  without  odor  and  is  inoffensive  in  every 
way,  to  the  place  of  discharge,  usually  on  a  lawn,  provided 
it  is  well  undertiled  and  drained,  or  in  a  pasture  or 
field." 

According  to  the  Bulletin  of  the  U.  S.  Department  of 
Agriculture  on  Water  Supply,  Plumbing  and  Sewage 
Disposal  for  Country  Homes,  "Single-chamber  septic- 
tank  systems  may  be  made  to  give  fair  satisfaction  if 
properly  designed  and  operated.     On  such  a  system  the 


DISPOSAL  OF  SEWAGE 


431 


sewage  is  received,  settled,  partially  purified,  and  dis- 
charged by  one  chamber. 


CAST  iRor^  coi^£:ff. 


^•:o-.:.;;.;«3;-.:  o/AMirTeff  /2' 


ri^m))))m)^i)kwA 


/f/f!/fV>->///r/n. 


CAST  IfPON 
CYUNDtf? 


ff^M  SEPTIC   TANK 


'WMm 


;'*:w  r.2'^  6  concrete 


h      3£CT/0N. 


TO   DISTRIBUTION 
BOTTOM     U 


i)mm)mm^^^^^^^^^^^^^^^^ 


PLAN. 
Fig.  122. — Plan  and  section  of  sewage-diverting  gate.     (U.  S.  Bulletin.) 


"There  is  necessarily  considerable  disturbance  of  the 
sewage  in  the  tank  and,  in  addition,  the  discharge  is  con- 


432     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

tinuous.  This  makes  necessary  two  disposal  systems, 
with  a  diverting  gate  to  allow  an  occasional  breathing 
spell  for  each  system.  If  such  an  arrangement  is  not 
used,  the  disposal  system  must  be  of  much  larger  capacity 


{?y^r£-  C/f/)/^3£-/? 


fh:>rr7  /an/r 


\ 


^"77'/c 


Fig.   123. — Ground  plans  of  tile  sewage-disposal  systems. 


than  for  the  double-chamber  tank  system  in  order  to 
prevent  the  continuous  discharge  from  waterlogging  the 
system. 

"  If  a  single  chamber  tank  is  used,  it  should  be  designed 
and  constructed  with  elbows  at  inlet  and  outlet  and 


THE  ASHLEY  SYSTEM  433 

with  baffle  boards  before  these  openings  to  break  up  the 
current." 

A  somewhat  similar  provision  for  the  disposal  of  the 
sewage  of  not  only  single  dwellings,  but  even  of  large 
institutions,  such  as  hospitals,  schools,  country  clubs,  etc., 
is  the  so-called  Ashley  system.  In  this  the  chief  features 
are  the  "biological  tank"  and  the  "nitrification  duct  or 
subsoil  bacteria  bed." 

In  the  former,  which  is  "so  constructed  as  to  induce 
rapid  sedimentation  of  the  solids  and  so  gauged  as  to 
produce  for  the  bacteria  the  most  favorable  conditions  for 
growth  possible,  without  consuming  all  the  oxygen  in  the 
sewage  before  discharging  the  tank  effluent  into  the  nitri- 
fication bed,"  the  anaerobic  action  takes  place  and  about 
one-fourth  to  one-third  of  the  purification  of  the  sewage  is 
effected.  The  latter,  which  "performs  the  final  and  real 
process  of  purification,"  by  oxidizing  and  nitrifying  the 
Hquefied  organic  compounds  coming  from  the  biological 
tank,  is  so  built  from  common  building  materials  as  to 
"  cause  the  liquids  to  be  completely  divided  and  scattered 
through  its  interior,  and  so  contrived  as  to  cause  air  to 
circulate  constantly  through  the  granular  materials  of 
which  the  duct  is  composed,  thereby  causing  a  very 
decided  aerobic  bacterial  action  therein  by  means  of  the 
trickling  fluids  coming  in  contact  with  the  aerobic  film 
covering  the  filtering  media."  The  final  product  is  practi- 
cally pure  water,  and  is  usually  taken  up  by  the  surround- 
ing soil,  making  it  unnecessary  in  most  cases  to  discharge 
it  into  a  neighboring  stream  or  lake. 

This  system  has  the  advantages  that  the  component 
parts  and  the  whole  are  always  planned  and  installed  for 
the  exact  work  which  it  has  to  do,  that  it  is  underground 
and  so  out  of  sight  and  inoffensive  in  every  way,  that  it 
is  not  affected  in  its  biological  functions  by  frost,  and  that 
it  practically  requires  no  attention  after  being  once  prop- 
erly constructed  and  installed.  A  half-hour's  time  once 
a  year  is  sufficient  to  care  for  an  ordinary  residential 
plant. 

28 


434     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 


"The  septic  tank,  although  air-tight  and  supposedly 
water-tight,  should  be  located  as  far  from  the  house  and  the 


RESULTS  OF  BIOLOGICAL  TREATMENT        435 

well  or  spring  as  convenience  and  local  surroundings  will 
permit,  thus  reducing  the  danger  of  pollution  or  nuisance 
in  case  of  leakage  or  improper  operation  of  the  system. 
The  sewer  from  the  house  should  be  of  vitrified  sewer 
pipe,  usually  of  4-inch  size,  with  tightly  cemented  joints, 
and  should  be  laid  to  a  grade  not  less  than  9  inches 
per  100  feet.  Where  the  fall  from  the  house  to  the  tank 
is  excessive,  it  is  a  good  idea  to  lay  the  last  100  feet 
of  tile  to  the  minimum  grade  to  break  up  entrance 
velocity."^ 

It  should  always  be  remembered  that  any  sewage- 
disposal  plant  can  only  do  a  certain  amount  of  work, 
and  therefore  must  be  designed  to  meet  the  conditions 
under  which  it  must  operate.  Regarding  these  condi- 
tions, Frankland  says:  "The  recent  experimental  work 
on  the  bacterial  treatment  of  sewage  .  .  .  shows  most 
conclusively  that  the  best  results  are  achieved  by  sepa- 
rating the  phases  in  which  the  bacterial  purification 
takes  place,  allotting  distinct  places  to  the  anaerobic  and 
the  aerobic  organisms  respectively  engaged  on  the  work. 

"The  anaerobic  bacteria  are  supplied  along  with  the 
sewage,  and  practically  no  difficulty  arises  in  retaining 
their  services  on  the  works  beyond  that  of  providing  them 
with  space  and  time  in  which  to  carry  on  their  labors. 
The  aerobic  bacteria,  however,  demand  air  in  addition  to 
space  and  time,  and  if  this  air  be  not  provided  in  sufficient 
quantities  they  go  on  strike,  and  leave  the  works,  their 
place  being  taken  by  their  less  exacting  anaerobic  brothers, 
who  are,  however,  unable  to  finish  the  work  of  purifica- 
tion. 

"  There  is,  then,  the  constant  tendency  for  the  overflow 
of  the  anaerobic  bacteria  into  the  aerobic  department  of 
the  works,  if  there  be  any  stinting  of  air  in  the  latter. 
In  order,  therefore,  to  insure  the  services  of  the  aerobic 
bacteria  being  retained  on  the  premises,  it  is  desirable  to 


'  United  States  Department  of  Agriculture,  Bulletin  on  Water  Supply, 
Plumbing,  and  Sewage  Disposal  for  Country  Houses,  p.  38. 


436     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

provide  for  the  aerobic  bacteria  at  least  two  workshops 
through  which  the  sewage,  on  coming  from  the  anaerobic 
department,  is  made  to  pass. 

"The  first  of  these  aerobic  workshops  it  may  be  diffi- 
cult to  provide  with  adequate  ventilation,  the  result  being 
that  both  anaerobic  and  aerobic  bacteria  will  here  be  found 
competing  with  each  other,  and  that  the  aerobic  organ- 
isms will  be  unable  to  complete  the  work  of  purification. 
The  sewage,  however,  on  passing  into  the  second  and 
better  ventilated  workshop  will  there  fall  almost  ex- 
clusively into  the  hands  of  aerobic  bacteria,  which  it  will, 
under  proper  management,  leave  as  an  inodorous,  almost 
pellucid  liquid  incapable  of  putrefaction."^ 

Another  writer  summarizes  as  follows:  "As  compared 
with  the  process  of  chemical  precipitation  and  sedimen- 
tation, the  bacterial  process  presents  the  following  advan- 
tages: (a)  It  requires  no  chemicals,  (b)  It  produces 
no  offensive  sludge,  but  only  a  deposit  of  sand  or  vege- 
table tissue  which  is  free  from  odor,  (c)  It  removes  the 
whole  of  the  suspended  matter,  instead  of  only  about 
80  per  cent,  thereof,  (d)  It  effects  the  removal  of  51.3 
per  cent,  of  the  dissolved  oxidizable  and  putrescible 
matter,  as  compared  with  the  removal  of  only  17  per  cent, 
effected  by  the  present  chemical  treatment,  (e)  The 
resultant  liquid  is  entirely  free  from  objectionable  smell, 
and  does  not  become  foul  when  it  is  kept;  it  further 
maintains  the  life  of  fish."^ 

The  following  table  of  results  is  given  as  an  example 
of  what  may  be  accomplished  by  a  proper  combination  of 
the  septic  tank  and  aerobic  filter-bed,  and  also  serves  to 
show  that  the  reduction  in  total  organic  solids,  free  ammo- 
nia, etc.,  is  not  entirely  completed  by  the  anaerobes  in  the 
former,  but  is  continued  by  the  later  action  of  the  aerobic 
organisms  when  they  are  given  opportunity  to  work: 


1  See  Francis  Wood's  Practical  Sanitary  Engineering,  p.  216. 

2  American  Year-book  of  Medicine  for  1900,  p.  549. 


RESULTS  OF  BIOLOGICAL  TREATMENT        437 

Table  Showing  Changes  in  Sewage  Under  Biological  Action. 
Parts  per  100,000. 


Sample. 


Sewage   . 

Septic  tank 
Filter,  1  foot 
Filter,  2  feet 
Filter,  3  feet 


Number 

of 
records. 

Organic 

solids  in 

Free 

Albumin- 
oid am- 
monia. 

suspen- 
sion. 

ammonia. 

18 

28.50 

2.164 

0.972 

16 

3.80 

1.716 

0.340 

!           16 

0.16 

0.036 

0.052 

16 

0.05 

0.020 

0.037 

i           16 

1 

0.06 

0.009 

0.031 

1 

Oxygen 
absorbed 
in  4  hours 
at  80°  F. 


5.019 

2.184 
0.328 
0.286 
0.244 


Disinfection  of  crude  or  effluent  sewage  may  at  times 
be  deemed  necessary  or  advisable.  For  this  purpose, 
various  agents  have  been  suggested  and  sometimes  used, 
but  on  the  basis  of  availabihty  and  expense,  especially 
where  considerable  quantities  of  sewage  are  involved  or 
the  treatment  is  to  be  more  or  less  continuous,  experience 
has  narrowed  the  selection  to  compounds  of  chlorine  and 
of  copper.  Of  these,  chlorinated  lime  (often  called  chloride 
of  lime  or  bleaching  powder)  and  copper  sulphate  are  the 
cheapest  and  most  used,  the  former  being  more  active, 
requiring  less  time  and  being  less  susceptible  to  organic 
matter.  As  in  all  other  efforts  at  disinfection,  sufficient 
of  the  germicidal  agent  must  be  used,  there  must  be 
thorough  mixing,  and  sufficient  time  for  action  must  be 
given  before  the  sewage  is  diluted  further  or  discharged 
into  a  stream.  The  quantity  of  disinfectant  needed  per 
million  gallons  of  sewage  will  depend  upon  the  state  or 
degree  of  clarification  of  the  latter,  but  with  a  good 
effluent  the  cost  of  disinfection  need  not  be  excessive. 

Electricity  has  also  been  suggested  as  an  agency  for  the 
purification  of  sewage,  but  in  most  localities  is  still  too 
expensive  for  the  purpose.  In  the  Webster  process  iron 
electrodes  are  used,  and  the  favorable  results  are  supposed 
to  be  due  partly  to  the  hypochlorites  which  are  formed 
from  the  chlorides  always  present  in  the  sewage,  and  partly 
to  the  carbonates  and  oxides  of  iron,  which  not  only 


438     THE  REMOVAL  AND  DISPOSAL  OF  SEWAGE 

deodorize  but  also  help  to  oxidize  rapidly  the  organic 
matters.  By  this  method  about  70  per  cent,  of  the  putres- 
cible  matters  and  almost  all  the  bacteria  are  removed 
from  the  sewage,  but  it  is  still  rather  costly  on  account 
of  the  large  amount  of  iron  consumed. 

The  selection  of  the  method  of  sewage  disposal  has  in 
the  past  been  made  too  hastily  or  without  sufficient  con- 
sideration by  some  communities,  with  correspondingly 
unsatisfactory  results.  In  all  cases,  careful  and  scientific 
tests,  covering  the  several  seasons  of  the  year,  and  taking 
into  consideration  local  conditions  and  factors,  should  be 
made  not  only  of  various  methods,  but  of  different  com- 
binations of  methods,  sufficient  time  being  taken  to  deter- 
mine the  value  of  each.  A  decision  arrived  at  in  this 
way  will  be  most  likely  to  prove  satisfactory  and  to  be  the 
most  economical  and  salutary  to  all  concerned. 

For  extended  discussion  of  the  problems  relating  to  the  removal, 
treatment  and  disposal  of  sewage,  the  reader  is  referred  to  the 
text-books  on  Sewerage  by  Folwell,  and  on  Sewage  Disposal  by 
Kinnicut,  Winslow  and  Pratt. 


CHAPTERXIII.         ^ 

INDUSTRIAL  HYGIENE  AND  OCCUPATIONAL 
DISEASES. 

The  marked  increase  in  recent  years  of  social  thought 
and  consideration  of  all  that  pertains  to  human  labor  have 
given  greater  and  wider  importance  to  the  subject  of 
industrial  hygiene  than  ever  before.  The  question,  ''Am 
I  my  brother's  keeper?"  has  a  novel  insistence,  and  the 
intimate  relationship  between  capital  and  labor,  employer 
and  employed,  and  the  community  and  the  worker  are 
more  clearly  defined. 

Moreover,  modern  conditions  present  new  problems. 
Complicated  machinery  has  supplanted  hand  labor  and 
complicated  processes  have  developed  from  those  that 
were  essentially  simple.  Busy  workshops  with  enlarged 
outputs  add  harmful  dusts,  vapors,  moisture,  etc.,  to  the 
environment  of  the  worker  far  beyond  the  safety  limit. 
Specialization  and  fast  speeding  keep  the  nerve  strain 
of  the  operatives  at  high  tension  for  long  hours.  Over- 
crowding in  factories  and  other  places  of  employment 
favors  insanitary  conditions  and  increased  danger  from 
infection  and  injury.  Transportation  adds  new  perils, 
as  electric  roads  are  added  to  those  of  steam  and  as 
motor  carriages,  trucks  and  cycles  and  self-propelled 
devices  of  all  kinds  multiply  beyond  number  on  streets 
and  roadways.  Carelessness  and  ignorance  jeopardize 
the  safety  of  the  new  laborer  or  of  him  who  does  not 
continually  appreciate  his  risks,  and  fatigue  is  a  positive 
factor  for  disaster,  as  is  shown  by  the  greater  proportion 
of  accidents  in  the  later  part  of  the  working  day. 

That  the  field  of  opportunity  and  service  is  enormous 
is  patent  when  we  realize  that  there  are  approximately 

(439) 


440  INDUSTRIAL  HYGIENE 

25,000,000  wage-earners  in  this  country  of  whom  more 
than  one-half  are  engaged  in  manufactures,  trade  and 
transportation,  and  that,  according  to  the  Efficiency 
Society,  "from  one-third  to  one-half  of  the  lives  of  all 
wage-earners  are  spent  in  their  places  of  occupation, 
generally  within  doors,  and  subject  not  only  to  industrial 
accident  but  also  to  lowered  vitality,  illness,  disorders 
and  diseases  arising  in  part,  at  least,  from  their  conditions 
of  employment."  Another  authority  states  that  30,000 
wage-earners  are  killed  and  1,500,000  wounded  by  indus- 
trial accidents  annually;  also  that  there  are  13,000,000 
cases  of  illness  annually  among  industrial  workers,  all  this 
representing  an  annual  financial  loss  of  nearly  $750,000,000. 
Moreover,  at  least  one-fourth  of  this  great  total  is  probably 
avoidable  and  almost  one-half  of  the  sickness  is  prevent- 
able. 

On  the  other  hand,  all  the  ills  and  disaster  that  befall 
wage-earners  must  not  be  attributed  to,  or  blamed  upon, 
their  occupations.  They  are  subject  to  the  insanitary 
conditions  of  their  homes  and  their  communities,  many  of 
these  under  their  tolerance  and  with  which  their  employ- 
ment or  employer  has  nothing  to  do.  They  are  liable  to 
the  same  infections  that  come  to  others  by  way  of  water 
or  food  or  through  contact.  Some  are  vicious  and  dis- 
sipated and  waste  their  health  and  lives  as  well  as  material 
substance  in  riotous  living.  Others  are  careless  and 
perhaps  ignorant  of  proper  sanitary  precautions  about 
the  home  and  concerning  the  person.  AH  these  may  have 
sickness  and  trouble  in  full  measure,  no  matter  what  their 
occupations. 

Even  in  the  factory  or  place  of  work,  the  harmful 
conditions  may  not  be  inherent  or  essential  to  the  occupa- 
tion. Only  one  part  or  process  of  an  industry  may  be 
dangerous,  and  this  risk  may  possibly  be  minimized  or  elimi- 
nated by  special  safeguards  and  extra  care.  Perhaps  the 
entire  nature  of  the  occupation  from  the  health  stand- 
point may  be  changed  by  proper  attention  to  cleanliness, 
ventilation  and  proper  humidity  of  the  atmosphere.    The 


OCCUPATIONAL  MORBIDITY  441 

removal  of  dust  by  readily  installed  blowers  and  conduits 
would  remove  the  harmful  feature  of  many  trades.  Per- 
haps the  length  of  working  day,  time  for  rest,  or  the  high 
tension  due  to  speeding,  rivalry,  or  even  the  temperament 
of  an  inconsidertae  employer  or  foreman  has  more  to  do 
with  causing  poor  health,  especially  among  women,  than 
the  work  itself.  Thus  due  thought  should  be  given  before 
an  occupation  is  clashed  as  necessarily  dangerous  or 
unheal  thful. 

For  the  same  reason,  caution  must  be  had  regarding 
the  inconsiderate  use  of  what  may  be  termed  the  vital 
statistics  of  occupations.  Many  statistical  tables  are 
fallacious  because  the  influence  of  important  and  varying 
factors  affecting  their  construction  has  been  overlooked. 
Thus,  age,  sex,  race,  heredity,  etc.,  all  help  to  determine 
the  healthfulness  and  the  length  of  life  of  an  individual 
perchance  even  more  than  does  the  nature  of  his  vocation. 
Add  to  these  the  effects  of  personal  habits,  home  sur- 
roundings, etc.,  upon  the  welfare  of  the  individual,  and  it 
will  be  seen  that  the  outside  influences  that  actually  modify 
the  health  or  the  longevity  of  a  large  proportion  of  the 
workers  in  a  given  occupation  must  be  many  and  positive. 
That  there  are  dangerous  trades,  harmful  processes  and 
devitalizing  pursuits,  no  one  denies.  The  caution  is  that 
we  do  not  seek  to  find  too  much  in  hastily  prepared  or 
carelessly  considered  tables  of  occupational  statistics, 
and  that  especial  care  be  had  in  comparing  the  life  data 
of  various  and  possibly  dissimilar  industries. 

Rosenau^  well  says  that  "in  order  to  improve  the 
hygienic  conditions  under  which  people  work,  and  in 
order  to  prevent  the  diseases  of  occupation,  five  funda- 
mental conditions  are  essential:  (1)  investigations;  (2) 
laws;  (3)  factory  inspection;  (4)  penalties;  (5)  education. 
It  is  self-evident  that  before  anything  may  be  accom- 
plished a  careful  study  must  be  made  of  the  facts.  These 
investigations  must  include  not  only  scient'fic  studies, 

1  Preventive  Medicine  and  Hygiene,  p.  915. 


442  INDUSTRIAL  HYGIENE 

but  economical  and  sociological  factors.  Suitable  laws  are 
necessary,  for  it  has  been  found  in  practice  that  the 
conditions  cannot  be  corrected  by  an  appeal  to  voluntary 
reform.  To  be  effective  the  laws  must  provide  ample 
ways  and  means  for  their  energetic  enforcement.  A 
systematic  factory  inspection  is  necessary  in  order  not 
only  to  protect  work  people  against  preventable  diseases 
of  occupation  and  to  correct  sanitary  defects,  but  also 
to  enforce  the  laws  concerning  hours  of  occupation,  child- 
labor  and  related  subjects.  These  laws  have  little  force 
unless  they  provide  a  penalty  both  against  the  employer 
and  the  employees.  Either  party  to  the  contract  should 
be  held  legally  responsible  in  case  of  violation.  Finally, 
education  directed  to  the  employer,  the  employee,  and  also 
to  the  public  at  large  is  necessary  to  obtain  and  sustain 
the  laws  and  maintain  the  standards." 

A  matter  of  much  importance  is  the  measure  of  the 
day's  work.  It  is  not  practicable  to  have  a  period  of 
fixed  duration  for  all  because  of  the  varying  conditions 
and  circumstances  in  different  employments  and  for 
the  same  employment  in  different  localities.  Necessity 
often  demands  long-continued  and  strenuous  effort  and 
this  may  be  the  routine  from  day  to  day,  but  wisdom 
indicates  that  the  customary  task  should  not  demand 
the  maximum  physical  or  nervous  effort  of  the  worker. 
There  should  be  a  constant  store  of  energy  in  reserve; 
in  fact,  where  possible,  an  increase  instead  of  a  depletion 
of  that  store. 

While  heavy  physical  labor  is  in  itself  exhausting  and 
should  limit  the  number  of  hours  of  work,  even  more 
so  is  work  requiring  fixed  mental  attention  and  activity 
or  high  nervous  strain,  and  if  both  muscle  and  brain  are 
heavily  taxed,  then  safety  demands  short  hours  with 
intervening  periods  of  rest  sufficient  for  thorough  repara- 
tion. On  the  other  hand,  where  the  demands  upon  the 
system  are  variable  in  their  intensity  and  more  or  less 
routine  and  automatic,  calling  for  no  extreme  or  long- 
continued  strain,  the  day's  work  may  be  long  and  yet 


WOMEN  AND  CHILDREN  443 

satisfactory.  Nevertheless,  there  should  always  be 
care  that  each  worker  should  have  his  full  quota  of  time 
for  healthful  sleep,  eating  and  the  proper  enjoyment 
of  life. 

In  many  trades  and  occupations  the  eight-hour  day 
has  been  adopted  or  the  tendency  toward  it  is  strong. 
This  has  meant  a  decided  change  in  many  instances  from 
former  custom  where  ten  hours  or  even  more  represented 
the  usual  day's  work.  But  from  carefully  collected 
reports  it  would  seem  that  if  due  attention  be  given  to 
details  and  essential  efficiency,  the  shorter  hours  may  be 
equally  advantageous  to  both  employer  and  employee, 
and  without  financial  loss  or  detriment  to  either.  In 
fact,  in  purchasing  labor  as  well  as  selling  it,  the  question 
of  fatigue  should  be  kept  in  mind.  When  the  worker 
tires  his  work  will  drag  and  will  not  be  as  efficient  as  when 
he  is  rested.  This  loss  coupled  with  the  cost  of  power, 
light  and  other  overhead  charges  for  the  extra  time  may, 
as  has  been  proved  in  a  number  of  establishments,  more 
than  counter-balance  the  apparent  loss  from  shorter 
hours.  Reference  has  already  been  made  to  the  increase 
in  factory  accidents  as  the  work-day  lengthens.  Work- 
men's compensation  laws  which  provide  for  the  recom- 
pense of  injured  employees  may  give  an  added  interest 
to  this  and  become  another  argument  for  shorter  hours. 

Women  and  Children. — Of  paramount  importance  in 
all  discussions  of  industrial  hygiene  are  the  questions 
that  pertain  to  the  labor  of  women  and  children.  So 
much  depends  upon  the  proper  conservation  of  all  the 
inherent  vigor  and  vitality  of  these  essential  elements 
of  the  body  politic  that  any  abuse  of  them  is  a  social 
crime  involving  harm  not  alone  to  the  weaker  members 
of  the  community  mass  but  to  all.  The  children  of  today 
are  the  adults  of  the  next  generation,  and  the  women 
are  the  potential  mothers  of  those  w^ho  are  to  follow. 
For  our  own  sakes  as  well  as  theirs  we  cannot  afford  to 
permit  practices  or  customs  that  tend  to  interfere  with 
the  education,  stunt  the  full  physical,  mental  and  moral 


444  INDUSTRIAL  HYGIENE 

development,  or  prematurely  age  and  weaken  the  vitality  of 
the  immature  members  of  society.  So,  with  equal  wisdom, 
must  provision  be  made  that  those  who  are  to  bear  the 
children  that  are  still  to  come  shall  have  every  reasonable 
protection  against  overtaxation  of  their  energies  and  what- 
soever may  tend  toward  the  degeneration  or  suicide  of 
the  race. 

According  to  Rosenau,  New  York  was  the  first  State 
in  this  country  to  pass  a  factory  act  regulating  child  labor. 
This  was  in  1886,  when  thirteen  years  was  fixed  as  the 
minimum  age  at  which  children  might  begin  to  work  in 
factories.  Since  then  many  other  States  have  passed 
similar  laws  and  in  almost  all  of  them,  as  well  as  now  in 
New  York,  the  minimum  age  has  been  placed  at  fourteen. 
A  number  of  the  States  regulate  the  number  of  hours 
per  day  and  per  week  during  which  the  child  may  work, 
and  some  prohibit  work  at  night,  especially  by  girls,  and 
in  certain  dangerous  trades  and  in  occupations  involving 
exposure  to  temptation.  In  Massachusetts  in  1910  "the 
State  Board  of  Health  was  given  power  to  declare  from 
time  to  time  whether  or  not  any  particular  trade,  process, 
of  manufacture,  or  operation,  or  any  particular  method  of 
carrying  on  such  trade,  process  of  manufacture,  or  operation 
is  sufficiently  injurious  to  the  health  of  minors  under 
eighteen  years  of  age  employed  therein  to  justify  their 
exclusion  therefrom. "^  The  Board  of  Health  has  power 
of  discretion,  however,  to  determine  whether  such  pro- 
cesses may  not  be  carried  on  with  reasonable  safety 
when  certain  precautions  are  observed  and  guaranteed. 
A  recent  innovation,  as  in  Pennsylvania  in  1915,  is  the 
requirement  that  children  at  work  between  the  ages  of 
fourteen  and  sixteen  shall  attend  continuation  schools 
for  a  specified  number  of  hours  per  week,  the  hours  of 
labor  being  lim'ted  accordingly. 

That  the  hours  of  women  who  labor  at  arduous  or 
exacting  trades  or  occupations  should  be  regulated  is  evi- 

^  Harrington,  Preventive  Hygiene,  5th  edition,  p.  678.     - 


FACTORY  SANITATION  445 

dent  to  every  student  of  the  question,  and  also  that 
reasonable  allowances  should  be  made  for  absence  or 
lessened  work  at  certain  periods.  Full  provision  for 
cessation  from  factory  or  similar  employment  with 
continuing  pay  both  before  and  after  child-birth  is  also 
essential.  The  Swiss  law  specifies  a  total  of  eight  weeks 
for  this  interim,  which  is  none  too  short  for  the  mother's 
future  health  and  safety.  Of  marked  importance  is  the 
influence  of  strenuous  labor  outside  of  the  home  upon 
both  the  birth-rate  and  infant  mortality.  Statistics 
show  that  it  is  very  much  to  society's  selfish  interest 
to  study  this  question  most  carefully  and  to  evolve 
necessary  laws  and  regulations  not  only  for  the  protection 
of  the  individual  women  who  must  work  for  a  wage,  but 
even  more  for  the  sake  of  its  own  ultimate  welfare  and 
safety.  Even  in  occupations  that  are  not  considered  extra 
hazardous  or  strenuous  and  that  seem  natural  or  appro- 
priate for  women,  there  is  much  room  for  consideration 
for  the  workers. 

Factory  Sanitation. — While  certain  occupations  must 
necessarily  be  dangerous,  in  spite  of  reasonable  precautions, 
because  of  poisonous  minerals  or  chemicals  or  harmful 
dusts,  gases  or  vapors  involved,  many  trades  or  pursuits 
that  have  hitherto  been  classed  as  unhealthful  have  been 
so  because  of  the  failure  to  maintain  ordinary  sanitary 
precautions  and  to  provide  proper  apparatus  for  adequate 
ventilation,  removal  of  dust,  regulation  of  humidity, 
etc.  A  dirty  factory  or  shop  in  a  dusty  trade  with  no 
sanitary  rules  or  orders  against  promiscuous  expectoration 
needs  only  one  tuberculous  employee  to  scalter  the  germs 
that  will  start  a  series  of  cases  that  persist  and  increase 
in  number  from  year  to  year  until  eventually  the  occupa- 
tion itself  is  looked  upon  as  dangerous  and  all  its  workers 
as  specially  liable  to  consumption.  And  so  with  other 
infections;  whereas  a  clean  shop  with  abundant  sunlight, 
good  ventilation,  careful  removal  of  dust,  and  strict 
orders  as  to  sanitary  personal  observances  under  penalty 
of  loss  of  employment  or  heavy  fines,   would  actually 


446  INDUSTRIAL  HYGIENE 

minimize  the  liability  to  infection  for  all  of  its  employees. 
So  novel  and  unusual  is  the  absolutely  clean  and  sanitary 
factory  that  even  n  those  trades  that  have  to  do  with 
the  preparation  or  conservation  of  our  food,  we  find  that 
cleanliness  is  made  a  matter  of  advertisement  and  as 
worthy  of  attracting  great  attention  instead  of  being 
taken  as  a  matter  of  course. 

So  common  have  been  the  faults  and  laxity  in  this 
respect  in  the  past  and  so  prone  is  human  nature  to  sacrifice 
the  welfare  of  both  employees  and  public  to  apparent  finan- 
cial profit,  that  competent  and  efficient  factory  inspection  is 
essential  in  order  that  the  rights  of  all  may  be  protected. 
Such  inspection  must  be  conversant  with  the  requirements 
of  the  law  in  all  its  details  as  it  applies  to  the  occupation 
and  particular  place  in  question,  and  must  deal  justly 
with  the  employer  as  well  as  the  employee,  and  particularly 
with  the  community  at  large,  which  may  have  more  at 
stake  than  either  of  the  two.  The  inspector  must  note 
the  provision  or  absence  of  all  that  makes  for  better  work, 
better  health  and  better  living,  and  for  such  a  sanitary 
state  that,  excepting  what  is  unavoidably  inherent  in  the 
nature  of  the  occupation,  disease  and  inipaired  health 
can  have  no  excuse  for  origin  or  persistence  in  that  factory 
or  shop.  One  particular  duty  of  the  inspector  will  be  to 
note  the  ages  and  the  hours  of  employment  of  working 
children;  another,  to  advise  and,  where  he  has  the 
authority,  to  insist  upon  such  devices  as  will  protect  the 
workers  against  preventable  accidents  as  well  as  harmful 
poisons,  dusts  and  vapors;  and  still  another,  to  collect 
and  collate  facts  and  data  upon  which  improved  legis- 
lation may  be  based  and  economic  and  social  progress 
may  be  advanced. 

Harmful  and  Dangerous  Occupations.— The  limitations 
of  the  present  work  do  not  permit  an  extensive  discussion 
of  even  the  more  important  occupational  diseases,  but 
some  suggestions  as  to  their  classification  may  enable 
the  reader  to  appreciate  their  extent  and  their  bearing 
upon  public  health  in  general. 


HARMFUL  AND  DANGEROUS  OCCUPATIONS     447 

Oliver  makes  the  following  general  subdivision:^ 

1.  Diseases  due  to  gases,  vapors  and  high  temperatures. 

2.  Diseases  due  to  conditions  of  atmospheric  pressure. 

3.  Diseases  due  to  metallic  poisons,  dusts  and  fumes. 

4.  Diseases  due  to  organic  or  inorganic  dust  and 
heated  atmospheres. 

5.  Diseases  due  to  fatigue. 

The  above  would  seem  to  overlook  the  infectious 
diseases,  such  as  anthrax,  tetanus,  glanders  and  hook- 
worm disease,  one  or  another  of  which  may  have  a  close 
relation  to  an  individual's  occupation.  Moreover,  a 
disease  may  have  such  varying  factors  as  to  place  it  in 
more  than  one  of  the  above  divisions. 

Hanson^  classifies  all  occupations  practically  as 
follows: 

"1.  Those  which  are  intrinsically  dangerous  to  health 
by  reason  of  the  nature  of  the  materials  involved,  or  by 
reason  of  the  conditions  which  arise  from  the  industry 
or  by  one  or  more  processes  of  the  industry. 

2.  Those  which  are  carried  on  under  conditions  which 
are  not  indispensable  to  the  industry  or  to  any  of  its  pro- 
cesses and  which  promote  susceptibility  to  disease. 

3.  Those  which  involve  exposure  to  mechanical  violence 
and  are  dangerous  to  life  and  limb  rather  than  to  health.'* 

The  difference  between  the  first  and  second  classes  is 
that  in  the  second  the  harmful  conditions  are  essentially 
avoidable,  while  in  the  first  class  some  of  the  factors 
are  unavoidable  while  others  may  or  may  not  be  so. 
The  third  class  scarcely  comes  in  the  domain  of  hygiene 
and  need  not  be  discussed  further. 

"  The  line  of  division  between  these  two  (first  and 
second)  classes  is  not  a  sharp  one,  and  some  occupations 
may  be  said  to  belong  to  both  classes.  For  the  purpose 
of  considering  the  specific  factors  in  industries  which  are 
inimical  to  the  health  of  the  workers,  occupations  may 
be  divided  into  the  following  groups: 

•  Rosenau,  loc.  cit.,  p.  922. 
'Harrington,  loc.  cit.,  p.  655. 


448  INDUSTRIAL  HYGIENE 

Group  I.  The  occupations  or  processes  which  are  of 
particular  hygienic  interest  and  give  rise  to  the  most 
clearly  defined  and  wide-reaching  occupational  diseases 
or  poisonings  are  those  which  involve  exposure  to — 

1.  Irritating  and  poisonous  dusts. 

2.  Irritating  and  poisonous  gases  and  fumes. 

3.  Infective  or  parasitical  matter  in  dust. 

4.  Abnormal  atmospheric  pressure. 

Group  II.  Of  distinct  importance,  though  not  always 
giving  rise  to  definitely  proved  occupational  diseases  or 
poisonings,  are  occupations  or  processes  which  involve — 

1.  Prolonged  use,  strain,  pressure,  fatigue. 

2.  Excessive  heat. 

3.  Dampness. 

4.  Offensive  gases  and  vapors. 

Some  occupations  are  conducted  under  such  con- 
ditions that  they  may  properly  be  regarded  as  belonging 
to  a  number  of  subgroups.  Mining,  for  example,  may 
be  considered  under  Group  I,  1,  2,  and  Group  II,  1,  2,  3,  4; 
and  cigar-making  under  Group  1, 1, 2, 3,  and  Group  II,  1."^ 

From  the  foregoing  it  will  be  noted  that  dust,  whether 
irritating,  poisonous  or  infective,  is  an  important  factor 
in  determining  the  healthfulness  of  many  occupations, 
and  that  if  its  prevention  or  prompt  removal  can  be 
provided  for,  what  has  been  looked  upon  as  a  dangerous 
trade  may  become  a  comparatively  innocuous  one. 
And,  as  such  prevention  and  removal  oftentimes  depends 
simply  upon  the  installation  of  proper  hoods  and  exhaust 
apparatus,  healthfulness  may  be  merely  a  matter  of 
reasonable  expenditure  of  money  and  strict  enforcement 
of  appropriate  legal  regulations. 

Likewise,  a  similar  enforcement  of  sanitary  provisions 
may  do  much  to  ameliorate  the  condition  of  the  workers 
in  those  pursuits  wherein  heat,  humidity  or  harmful 
gases  and  vapors  are  the  harmful  factors,  and  to  develop 
a  sane  appreciation  of  the  value  of  the  health  of  the 

^  Harrington,  loc.  cit.,  p.  656. 


POISONOUS  METALS  449 

laborer  as  contrasted  with  the  comparatively  small  outlay 
necessary  to  bring  about  and  maintain  the  improved 
conditions. 

Reference  has  been  made  in  another  chapter  to  the 
fact  that  dust  made  up  of  hard  and  sharp  particles  is  more 
irritating  and  harmful  than  that  in  which  they  are  soft 
and  smooth.  Thus,  it  has  long  been  known  that  workers 
in  metallic  dusts  had  a  high  incidence  of  both  pneumonia 
and  phthisis,  and  that,  other  factors  being  equalized,  the 
frequency  of  the  latter  disease  decreased  in  various 
occupations  accordingly  as  the  dust  particles  became 
softer  and  less  angular  as  well  as  less  in  quantity. 

To  enumerate  all  occupations  or  processes  in  which 
dust  is  prevalent  and  harmful  would  be  difficult.  Among 
the  most  important  of  these,  however,  may  be  mentioned 
steel  grinding  of  all  kinds,  glass  grinding,  pearl-button 
making,  stone  cutting,  w^ork  in  tobacco  factories,  cotton 
or  linen  mills,  and  where  chemical  or  poisonous  dusts 
are  prevalent. 

The  poisonous  metals  most  frequently  used  commercially 
are  probably  lead,  arsenic,  phosphorus,  chromium  and  mer- 
cury. Of  these  the  first  two  may  be  carried  into  the  system 
in  the  form  of  dust,  although  they  are  also  ingested  in  other 
ways;  the  other  three  are  usually  absorbed  through  the 
skin  and  mucous  membrane  of  the  mouth  or  are  taken  in 
as  fumes  and  vapors.  Lead  is  employed  in  a  very  large 
number  of  trades  and  processes — probably  over  100 — so 
that  cases  of  lead  poisoning  are  by  no  means  uncommon. 
Frequently  the  patient  has  only  his  own  carelessness 
to  blame  for  his  ill-health,  but  it  is  also  often  due  to  the 
lack  of  proper  precautions  and  hygienic  control  of  con- 
ditions on  the  part  of  the  employer.  In  many  cases  of 
lead  poisoning,  the  metal  has  entered  the  system  in  the 
form  of  dust  or  fumes,  and  seems  to  be  more  dangerous 
in  this  way,  the  absorption  probably  occurring  through 
the  lungs  as  well  as  stomach.  On  the  other  hand,  it 
is  frequently  ingested  by  the  mouth,  being  carried  thither 
on  soiled  hands  or  fingers;  in  these  cases,  attention  to 
29 


450 


INDUSTRIAL  HYGIENE 


ordinary  hygienic  precautions  on  the  part  of  the  workers 
should  prevent  a  large  proportion  of  the  cases,  and  the 
use  of  proper  respirators  should  be  equally  efficacious 
with  regard  to  those  of  the  first  class.  In  all  places  where 
the  workers  handle  or  come  in  contact  with  lead  ample 


^  Fig.  125. — Steel  and  iron  workers  at  emery  wheels.  Showing  effec- 
tive front  and  side  guards  for  their  protection  against  the  inhalation  of 
dust  particles.  (Illustration  supplied  by  Dr.  W.  C.  Hanson  for  Massa- 
chusetts State  Board  of  Health.) 

provisions,  including  a  supply  of  hot  water  and  soap, 
should  be  made  for  washing  and,  in  some  cases,  bathing, 
and  those  exposed  to  the  metal  should  be  required  to  make 
frequent  and  regular  use  of  such  provisions.  Eating 
places  should  be  entirely  apart  from  the  place  of  work. 


HARMFUL  AND  DANGEROUS  OCCUPATIONS    451 

The  occurrence  of  phosphorus  poisoning  has  been  greatly 
lessened  in  recent  years  by  the  prohibition  in  a  number 


Fig.  12G. — Lead  working  in  the  manufacture  of  storage  batteries. 
In  mixing  peroxide  of  lead  and  litharge  employees  are  exposed  to  lead 
poisoning.  The  employee  shown  was  wearing  a  respirator,  but  was  not 
willing  to  wear  long  gloves.  (Illustration  supplied  by  Dr.  W.  C.  Hanson 
for  Massachusetts  State  Board  of  Health.) 


452  INDUSTRIAL  HYGIENE 

of  European  countries  of  the  use  of  white  phosphorus 
in  the  manufacture  of  matches,  and  by  a  heavy  tax  upon 
their  manufacture  in  the  United  States  and  federal 
laws  forbidding  their  importation  after  January  1,  1913 
and  their  exportation  after  January  1,  1914.  So  also 
processes  in  which  mercury  poisoning  formerly  occurred, 
such  as  gilding  and  mirror  making,  have  been  so  changed 
that  few,  if  any  cases  now  occur  in  those  trades.  There 
is  still  some  risk  in  the  felting  industry  in  which  the  fur 
or  hair  is  sometimes  treated  with  mercuric  nitrate,  and 
in  occupations  in  which  metallic  mercury  and  amalgam 
is  much  handled.  Arsenic  is  used  in  a  large  number  of 
trade  processes  and  in  those  in  which  much  dust  is  preva- 
lent, there  may  be  considerable  risk  to  the  workers. 

Chromium  is  used  in  the  tanning, industry  and  is  a 
cause  of  local  inflammations  of  the  skin  and  mucous 
membranes,  causing  severe  and  intractable  ulcers. 

The  list  of  occupations  in  which  the  prevalence  of 
irritating  or  poisonous  gases  or  fumes  is  a  factor  in  causing 
ill-health  among  the  workers  is  a  long  one.  Carbon 
monoxide,  from  whatever  source,  is  a  very  dangerous 
gas,  and  so  is  chlorin,  Pettenkofer  asserting  that  60 
parts  of  the  latter  gas  in  100,000  of  air  will  cause  death. 
Fumes  from  the  strong  acids,  nitric,  sulphuric  and  hydro- 
chloric, are  intensely  irritating,  as  is  ammonia,  and  may 
cause  acute  or  chronic  respiratory  trouble.  Other  sub- 
stances used  commercially  and  giving  off  dangerous  or 
harmful  gases  or  vapors  are  wood  alcohol,  naphtha, 
nitrobenzol,  aniline  and  other  nitro  derivatives,  carbon 
disulphide,  etc.,  and  anyone  of  these  may  be  the  cause  of 
most  serious  or  fatal  results.  The  importance  of  frequent 
and  thorough  examinations  of  all  who  work  in  the  pres- 
ence of  poisonous  metals  or  vapors  should  be  emphasized 
and  the  duty  impressed  on  those  who  are  apt  to  develop 
a  false  sense  of  security  through  carelessness,  habit  and 
familiarity  with  the  respective  dangers. 

Tuberculosis  can  scarcely  be  considered  an  occupational 
disease  but  it  is  the  chief  cause  of  death  in  many  occupa- 


GENERAL  PROPHYLAXIS  453 

tions  where  dust  is  excessive  and  irritating  and  where 
rules  against  expectoration  and  uncleanliness  are  not 
enforced.  Maladies  more  truly  related  to  occupation  are 
anthrax,  which  may  occur  among  those  who  handle 
hides,  horse-hair  and  wool,  and  glanders  and  foot-and- 
mouth  disease,  to  which  hostlers  and  stockmen  are  exposed. 
Ankylostomiasis  or  hook-worm  disease,  while  prevalent 
in  the  southern  United  States  and  in  certain  parts  of 
Europe,  frequently  occurs  among  tunnel-  and  mine- 
workers,  and  hence  is  sometimes  called  miner's  anemia. 
It  is  evident  that  the  incidence  of  the  foregoing  and  all 
other  parasitic  occupational  diseases  may  be  greatly 
lowered  by  disinfection  and  other  prophylactic  measures. 

So  also  the  means  of  prevention,  protection  or  improve- 
ment in  diseases  due  to  excessive  heat  or  humidity,  or  to 
fatigue,  strain,  posture,  etc.,  are  obvious  and  the  long 
list  of  such  affections  need  not  be  detailed  here.  A 
peculiar  malady  is  that  to  which  workers  in  compressed 
air,  as  in  caissons  and  under-river  tunnels,  are  subject. 
It  comes  on  after  the  worker  returns  to  atmosphere  under 
normal  pressure,  and  is  marked  by  headache  and  severe 
pains  in  the  back,  legs  and  abdomen,  rapid  pulse,  sweating 
and  more  or  less  motor  paralysis.  Death  may  occur  in 
a  short  time  in  some  cases,  but  most  cases  recover  com- 
pletely, especially  under  treatment,  which  consists 
mainly  in  subjecting  the  patient  again  to  the  high  pressure 
and  then  reducing  it  very  gradually. 

Regarding  prophylaxis  in  general,  the  following  by 
Hanson  is  most  appropriate.^ 

"  It  will  be  noticed  that  the  disastrous  effects  attributed 
to  occupations  are  in  very  large  part  due  to  non-observ- 
ance of  the  principles  of  general  hygiene,  and  chiefly  to 
inattention  to  that  most  important  sanitary  measure, 
perfect  ventilation.  It  will  have  been  noted  that  the 
conditions  which  bring  about  impairment  of  health  may 
be  reduced  very  largely  by  a  constant  supply  of  fresh  air. 

'  Harrington,  loc.  cit.,  p.  677. 


454  INDUSTRIAL  HYGIENE 

With  proper  attention  to  this  matter  and  improvement 
in  the  home  and  home  influences,  greater  attention  to 
the  character  and  preparation  of  food,  and  a  more  general 
observance  of  the  beneflcial  influence  of  active  out-door 
exercise,  no  very  great  difference  would  be  noted  in  the 
health  of  the  various  classes  of  work  people,  and  the 
expression,  occupational  diseases,  would  lose  whatever 
significance  it  now  has." 

On  the  other  hand,  however,  all  that  pertains  to  in- 
dustrial hygiene  will  be  a  matter  of  moment  and  real 
importance  to  all  who  are  interested  in  the  public  welfare 
and  the  health  of  the  body  politic,  and  whether  that 
interest  be  chiefly  in  the  line  of  investigation,  legislation, 
industrial  supervision  or  popular  education,  much  remains 
to  be  accomplished  before  conditions  can  be  satisfactory 
and  sanitary  for  the  worker  and  conducive  to  the  safety 
and  common  health  of  the  general  community  in  which 
he  lives.  Proper  protection  for  the  adult  men  as  well  as 
for  the  women  and  children,  proper  allotment  of  time 
for  rest  and  recreation  as  well  as  for  work,  and  proper 
attention  to  all  details  that  affect  the  bodily  health  of 
each  one  who  labors  at  a  daily  task  are  essential  in  order 
that  the  public  at  large  may  be  safe  and  truly  prosperous. 


CHAPTER  XIV. 
MILITARY  HYGIENE. 

This  subject  is  one  which  has  to  do  with  active  and 
presumably  healthy  men  under  conditions  more  or  less 
abnormal  and  sometimes  of  a  peculiar  and  unusual  stress. 
Moreover,  the  actual  financial  value  of  the  life  and  health 
of  the  individual  to  the  State  is  more  directly  manifest 
than  under  ordinary  circumstances,  and,  though  at  times 
the  interests  of  the  former  must  be  sacrificed  to  those  of 
the  latter,  it  is  of  the  highest  economic  and  practical 
importance  that  a  government  should  conserve  as  far  as 
possible  the  health  and  welfare  of  each  member  of  its 
army  and  navy.  Consequently,  much  thought  should  be, 
and  is,  given  to  all  those  questions  which  rightly  come 
under  this  head,  and  the  effect  of  the  efforts  made  in  this 
direction  is  very  marked,  especially  with  reference  to  the 
regular  or  standing  armed  force  of  the  country. 

Mer^  who  have  become  accustomed  to  military  service, 
and  to  whom  it  is  a  real  and  permanent  business,  have 
probably  a  better  health  status  than  the  average  citizen, 
owing  to  the  regularity  of  their  habits  and  work  and  to 
the  oversight  and  care  which  are  given  to  the  details  of 
their  life.  Conditions  are  much  different,  however,  when 
men  are  suddenly  called  from  many  occupations  and  ways 
of  living  to  active  army  or  naval  service.  They  do  not 
accommodate  themselves  readily  to  the  change,  nor  do 
they  appreciate  the  importance  of  details  that  may  seem 
trivial  to  them  but  that  have  great  bearing  on  their  future 
health.  Often  the  utmost  efforts  on  the  part  of  those  in 
authority  and  who  are  skilled  in  these  matters  are  appar- 
ently of  no  avail  and  lead  to  undeserved  censure.    How 

(455) 


456  MILITARY  HYGIENE 

much  more  serious  actual  neglect  of  hygienic  measures 
may  be  has  been  proved  more  than  once  in  the  past. 

The  following  quotation  from  the  Report  of  the  Sur- 
geon-General of  the  Army  for  1899  is  as  pertinent  to-day 
as  when  written: 

"Hygiene  is  one  of  the  principal  subjects  of  examina- 
tion for  candidates  desiring  appointment  in  the  medical 
corps  of  the  army,  and  at  the  subsequent  examinations  for 
promotions  to  the  grades  of  captain  and  major  it  is  given 
a  most  prominent  place.  It  is  also  the  most  prominent 
subject  in  the  course  of  instruction  at  the  Army  Medical 
School,  where  the  student  officers  spend  five  hours  daily 
for  a  period  of  five  months  in  practical  laboratory  work 
relating  for  the  most  part  to  the  cause  and  prevention  of 
infectious  diseases;  but  the  comparatively  small  number 
of  medical  officers  of  the  regular  army  available  for  duty 
in  the  large  camps  occupied  by  our  volunteer  troops  at 
the  outset  of  the  war  (Spanish-American)  proved  to  be 
entirely  inadequate  to  control  the  sanitary  situation  in 
these  camps." 

In  a  study  of  military  hygiene,  all  phases  of  the  routine 
life  of  the  soldier  should  be  discussed,  for  it  is  the  combi- 
nation of  these  that  make  for  good  or  ill. 

Unless  the  emergency  is  grave  and  large  numbers  of 
men  are  needed  quickly,  much  attention  should  be  paid 
to  the  selection  of  the  men,  and  only  those  enlisted  who 
satisfy  certain  physical  requirements.  They  should  be 
neither  abnormally  short  nor  tall;  the  weight  should  be 
in  proper  ratio  to  the  height;  the  vision  and  general  health 
good,  and  especially  should  the  chest  measurement  and 
expansion  or  "vital  capacity"  be  considered  as  of  great 
importance. 

"It  has  also  been  observed  that  a  close  correlation 
exists  between  the  physical  and  moral  development  of 
men;  in  fact,  lowering  the  physical  means  lowering  the 
moral  standard  of  recruits."^ 

1  Notter  and  Firth,  p.  917. 


EXAMINATION  AND   SELECTION  OF  RECRUITS     457 

Age  is  also  a  factor  that  should  be  considered.  If 
recruits  are  too  young,  they  are  not  able  to  withstand 
long-continued  work  or  strain,  nor  will  they  be  so  likely 
to  resist  the  incurrence  of  disease.  On  the  other  hand, 
men  who  are  too  old  will  be  more  liable  to  have  habits  of 
life  or  taints  of  chronic  disease  that  will  interfere  with 
their  military  duty,  and  they  will  also  not  serve  the 
maximum  length  of  time  that  makes  their  work  most 
economical  to  the  government.  It  was  chiefly  for  these 
reasons  that  the  limits  of  age  for  those  first  called  into 
the  national  selective  army  were  fixed  at  twenty-one  and 
thirty-one  years,  and  it  is  fortunate  that  the  war  termin- 
ated before  there  was  great  and  continued  need  for  many 
men  below^  the  former  or  above  the  latter  age. 

"The  experience  of  the  U.  S.  Army  and  of  all  other 
armies  is  that  the  admission  rate  to  sick  report  is  highest 
for  young  soldiers  under  twenty  years  of  age.  This  is 
especially  true  of  typhoid  fever.  The  death-rate  is  highest 
in  young  soldiers,  nineteen  years  and  under,  but  declines 
after  twenty  and  reaches  its  minimum  between  twenty- 
five  and  thirty  years,  rising  again  slowly  up  to  forty  years 
and  rapidly  thereafter.  "^ 

"  The  medical  officer's  first  duty  is  to  rigorously  examine 
his  command,  if  it  has  been  newly  raised,  and  inexorably 
to  eliminate  all  men  unfit  for  full  military  duty.  Upon 
the  medical  officer  who  examines  recruits  for  enlistment 
lies  a  heavy  responsibility,  for  it  practically  rests  with 
him  to  determine  the  physical  efficiency  of  the  command. 
Unfortunately  in  time  of  war,  when  the  necessity  for 
effective  men  is  the  greatest,  this  selection  is  apt  to 
devolve  upon  untrained  civilians  who  have  neither  the 
special  knowledge  that  fits  them  as  judges  nor  the  position 
that  enables  them  in  doubtful  cases  to  withstand  the  con- 
stant importunities  of  still  less  informed  recruiting  officers. 
The  careful  examination  of  recruits  is  not  practical  hygiene, 

1  Havard's  Military  Hygiene,  Second  edition,  p.  16. 


458 


MILITARY  HYGIENE 


but  the  successful  application  of  hygiene  requires  carefully 
selected  men  to  secure  the  best  results."^ 

That  this  is  so  was  shown  by  the  rejection  by  the  final 
examining  boards  of  the  Army  of  a  large  number  of 
the  men  who  had  already  been  passed  by  the  selective 
draft  boards  of  their  respective  localities.  At  least  one 
of  each  draft  board  was  a  physician,  and  while  there  is 
no  question  as  to  the  purpose  and  desire  of  practically 
all  of  these  to  decide  honestly  and  to  the  best  interests 


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Fig.  127. — Settiu<i;-iip  exercises,  the  first  part  of  the  daily  drill. 


of  the  country,  there  were  many  cases  in  which  their 
judgment  concerning  the  qualifications  of  the  prospective 
soldiers  was  decidedly  faulty  and  unsatisfactory. 

"The  most  frequent  single  cause  for  rejection  is  defective 
development;  during  1898  more  than  a  fourth  of  the 
rejections  of  candidates  for  the  regular  army  were  made 
on  this  ground.     Second  in  order  was  defective  vision; 

1  Colonel  A.  A.  WoodhuU,  article  on  Military  Hygiene  in  Reference. 
Hand-book  of  the  Medical  Sciences. 


EXAMINATION  OF  RECRUITS  459 

third,  diseases  of  the  circulation.  Other  causes,  in  order, 
were  diseases  of  the  genito-urinary  organs,  diseases  of 
the  digestive  apparatus,  bad  character,  general  unfitness, 
deafness,  and  illiteracy.  Men  of  defective  development, 
if  admitted  are  noted  for  the  time  which  they  spend  in  the 
hospital  and  in  the  guard-house.  Another  element  which  it 
is  most  important  to  exclude  is  the  habitually  intemperate."^ 

The  chief  causes,  however,  of  the  discharges  in  1917 
were  tuberculosis  (23.15  per  cent.),  organic  diseases  of 
the  heart  (9.02  per  cent.),  flat  feet  (8.78  per  cent.),  mental 
deficiency  (6.37  per  cent.)  and  epilepsy  (3.95  per  cent.). 

The  Report  of  the  Adjutant-General  of  the  Army  for  the 
fiscal  year  ending  June  30,  1917,  states  that  "49  per  cent, 
of  those  who  applied  for  enlistment  at  the  recruiting 
station  were  accepted  and  that  9  per  cent,  of  the  accepted 
applicants  were  afterward  rejected  upon  examination  at 
depots.  For  the  preceding  fiscal  year  the  corresponding 
percentages  w^ere  23  and  13,  respectively."  This  was 
before  the  draft  boards  had  begun  to  function,  but  the 
Report  of  the  Surgeon-General  of  the  Army  for  the  fiscal 
year  ending  June  30,  1918,  states:  "The  work  of  making 
the  physical  examinations  has  been  faithfully  done,  but 
it  has  failed  sufficiently  to  sort  out  the  fit  and  the  unfit 
for  warfare.  This  partial  failure  must  be  ascribed  to  the 
fact  that  making  physical  examinations  on  so  great  a  scale 
was  a  new  experience  for  most  of  the  physicians  engaged. 
It  was  impossible  for  the  number  of  experienced  men 
available  to  make  the  examinations  properly  in  the  time 
allotted.  Consequently,  many  men  were  passed  with 
defects  and  diseases  undetected."  Again,  speaking  of  the 
large  number  of  men  discharged  in  that  year  from  the 
Army,  the  Surgeon-General  says:  "The  apparent  reason 
for  this  large  number  of  discharges  was  the  military 
necessity  of  hastily  inducting  into  the  service  a  large 
number  of  men  often  with  imperfect  examinations." 


1  Harrington   and   Richardson,    Practical  Hygiene,  5th  ed.,  pp.  712 
and  713. 


460  MILITARY  HYGIENE 

"It  is  not  believed  to  be  good  policy  to  enlist  men 
who,  though  able-bodied  and  intelHgent,  appear  at  re- 
cruiting stations  in  ragged  or  filthy  dress,  as  the  chances 
are  such  men  are  tramps  and  vagabonds  and  will  not 
make  good  soldiers.  Men  who,  though  attired  in  clean 
and  respectable  clothing,  are  found  to  be  filthy  in  their 
persons,  should  be  promptly  rejected  for  like  reason. "^ 

Harrington  also  says  of  the  enlisted  man:  "Personal 
cleanliness  is  of  great  importance  in  the  maintenance  of 
health  and  efficiency  and  should  be  the  subject  of  much 
attention  on  the  part  of  inspecting  officers." 

One  of  the  essential  qualities  of  a  good  soldier  is  self- 
respect  and  pride  in  himself  as  a  worthy  member  of  his 
organization.  It  may  be  necessary  to  be  unclean  at 
times  and  for  considerable  periods  when  in  active  service, 
but  there  should  be  no  laxity  whenever  conditions  render 
such  a  state  unnecessary. 

Men  of  intemperate  habits  may  sometimes,  through 
latent  force  of  character  or  under  army  control  and 
discipline  make  good  soldiers,  but  drug  addicts  should 
be  unhesitatingly  rejected,  as  the  probability  of  satisfac- 
tory service  on  their  part  is  almost  negligible  and  as  they 
are  almost  certain  to  cause  disturbance  and  trouble. 

In  selecting  the  sites  for  camps  or  homes  of  soldiers, 
consideration  must  be  had  as  to  whether  these  are  to  be 
temporary  or  permanent,  and  as  to  whether  the  men  are 
to  live  in  tents  or  barracks.  In  any  case,  there  should  be 
sufficient  space  allotted  to  each  command;  there  should 
be  no  interference  with  the  free  circulation  of  air,  and 
the  soil  should  be  dry,  porous,  and  readily  drained.  The 
ground-water  especially  should  not  be  too  near  the  sur- 
face. Camps  should  not  be  located,  except  in  event  of 
grave  military  necessity,  on  ground  that  has  been  recently 
occupied  by  other  troops;  nor  should  they  be  on  clay 
soils,  in  ravines  or  valleys  where  they  will  receive  the 
drainage  from  higher  ground  or  other  camps,  nor  near 

1  Manual  for  the  Medical  Department,  Washington,  1898,  p.  65. 


CAMP-SITES  461 

marshes  or  the  marshy  banks  of  rivers,  nor  where  they 
will  receive  the  winds  and  mosquitoes  from  malarial  dis- 
tricts. Thought  should  also  be  given  to  the  source  and 
abundance  of  the  water-supply  and  its  relation  to  the 
natural  course  of  drainage  from  the  camp. 

If  tents  are  to  be  used,  these  must  be  such  as  to  afford 
both  thorough  protection  and  good  ventilation.  They 
should  not  be  too  crowded,  either  as  regards  the  number 
of  occupants  in  each  or  the  location  of  the  tents  one  to 
another.  If  the  camp  is  to  be  of  extended  duration,  the 
tents  should  be  floored,  or  at  least  the  men  should  not  sleep 


A  well-policed  company  street. 


on  the  ground.  Although  the  construction  of  wooden  bar- 
racks was  soon  found  to  be  necessary  as  well  as  advisable 
in  the  large  concentration  camps  throughout  the  countrs', 
many  tents  were  also  required  and  at  times  a  sufficient 
number  were  not  at  once  available,  so  that  the  problem 
of  overcrowding  was  sometimes  a  serious  one.  But  one 
advantage  of  a  tent  is  the  opportunity  for  good  ventila- 
tion if  this  be  ensured  by  strict  regulations  and  persistent 
vigilance. 

A  trench  should  also  be  dug  about  each  tent  to  prevent 
flooding  by  rains,  and  from  time  to  time  the  tents  should 


462 


MILITARY  HYGIENE 


be  moved  about,  as  "it  is  well  known  that  tents  occupy- 
ing the  same  ground  for  a  length  of  time  become  un- 
healthy."    Camp  kitchens,  stables,  sinks,  latrines,  etc., 


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Distances  in -yards.  Dimensions  of  Camp  300  «260  yards. 

For  55  men  to  the  company   Each  additional  tent  per  company  increases  the 
width  of  the  Camp  8  yards. 

Fig.  129. — Camp  of  a  regiment  of  infantry. 


CAMP  ARRANGEMENT  463 

should  be  as  far  from  the  sleeping  tents  as  reasonable 
convenience  permits,  and  to  the  leeward  of  prevailing 
winds.  All  camps  should  be  regularly  and  carefully 
policed,  and  "the  fact  that  a  camp  expects  to  change  its 
position  does  not  justify  neglect  of  proper  policing  of  the 
ground    occupied." 

In  the  regulations  and  instructions  issued  in  1895  by 
the  British  Quartermaster-Generars  Department  the  fol- 
lowing points  are  laid  down  as  of  importance: 


•     Fig.  130. — A  company  street  for  a  cold  weather  camp. 

"  (1)  The  length  of  time  troops  are  to  occupy  the  camp- 
ing-ground. (2)  That  order,  cleanliness,  ventilation,  and 
salubrity  are  to  be  insured.  (3)  That  means  of  passing 
freely  through  the  camp  are  essential.  (4)  That  a  strag- 
gling camp  increases  labor  of  fatigue  duties,  and  impedes 
delivery  of  supplies  and  circulation  of  orders.  (5)  That 
the  more  compact  the  camp,  the  easier  it  is  to  defend."^ 

1  Notter  and  Firth,  p.  936. 


464  MILITARY  HYGIENE 

If  the  soldiers  are  assigned  to  forts  or  other  permanent 
encampments,  they  will  probably  be  quartered  in  barracks, 
and  these  will  have  been  constructed  according  to  specifi- 
cations. However,  it  should  be  remembered  that  in  these 
attention  must  be  given  not  only  to  the  comfort  of  the 
men,  but  to  their  sanitary  needs  ^s  well,  and  that  the 
chief  faults  in  such  structures  in  the  past  have  been  insuffi- 
cient ventilation  and  improper  location  and  arrangement 
of  toilet-rooms,  etc. 

Barrack  buildings  should  not  be  more  than  two  stories 
in  height,  should  be  comparatively  narrow,  should  have 
free  ventilation  and  access  of  sunlight  about  them,  and 
should  be  so  placed  that  they  do  not  interfere  with  one 
another  in  these  respects.  It  will  be  well  if  each  sleeping- 
room  is  planned  to  contain  not  more  than  twenty-five  or, 
at  most,  fifty  men.  Each  man  should  have  at  least 
600  cubic  feet  of  air-space  in  his  dormitory;  with  ceilings 
twelve  feet  high,  this  will  give  him  fifty  square  feet  of 
floor-space.  Toilet-rooms  should  be  separated  from  the 
dormitories  by  a  continually  ventilated  passage-way,  at 
least;  it  would  be  better  to  have  the  former  entirely  apart 
from  the  latter. 

Kitchens,  dining-  or  mess-rooms,  guard-rooms,  and 
quarters  for  married  men  should  be  in  separate  buildings 
and  apart  from  the  barracks,  and  these  should  each 
be  properly  arranged  for  its  purpose.  The  same  remarks 
apply  to  the  post-hospital,  which  should  have  as  complete 
an  equipment  as  possible  in  accordance  with  the  demands 
of  modern  medical  and  surgical  science;  and  conse- 
quently, in  addition  to  the  general  wards,  there  should  be 
others  for  the  isolation  of  contagious  or  infectious  cases 
and  for  the  insane.  It  goes  without  saying  that  the 
officers'  quarters  should  have  every  hygienic  and  sanitary 
advantage  and  convenience,  both  as  to  construction  and 
location,  that  the  circumstances  of  the  post  will  permit. 

In  such  permanent  encampments,  where  the  accommo- 
dations and  conveniences  more  nearly  resemble  those  in 
the  home  of  the  average  private  citizen,  and  where  proper 


PERMANENT  ENCAMPMENTS  465 

food,  an  ample  supply  of  unpolluted  water,  and  suitable 
arrangements  for  the  removal  of  wastes  and  sewage  can 
all  be  provided  for,  it  will  ordinarily  not  be  difficult  for 
the  well-informed  medical  officer  to  maintain  a  satisfactory 
sanitary  condition,  and,  owing  to  the  discipline  and  super- 
vision of  their  habits  to  which  the  men  are  subjected,  as 
well  as  to  the  fact  that  they  are  adults  and  males,  the 
general  health  status  of  the  post  should  usually  be  better 
than  the  average  of  the  neighboring  communities. 

But  conditions  and  circumstances  are  much  different  on 
the  "tented  field,"  and  especially  so  if  the  command  belong 
to  the  militia,  volunteer  or  selective  (draft)  service,  in  which 
the  men  have  been  called  from  many  and  various  occupa- 
tions, are  unaccustomed  to  the  hardships  of  military  life  and 
the  vicissitudes  of  out-door  living,  and  are  unmindful — 
as  they  will  be  at  first — of  the  restraints  and  value  of  dis- 
cipline. Even  though  the  medical  officers  be  well  versed 
in  hygienic  knowledge  and  thoroughly  aware  of  the  im- 
portance of  the  strict  observance  of  sanitary  precautions, 
and  though  they  have  the  hearty  assistance  of  the  com- 
manding officers,  it  will  take  much  time  so  to  instruct  the 
men  that  they  will  not  endanger  the  health  of  themselves 
and  others,  and  eternal  vigilance  and  much  effort  will  be 
the  price  of  a  continuously  satisfactory  state  of  affairs. 

"In  time  of  war  there  is  added  a  new  army  of  volun- 
teers, whose  men  are  often  accepted  without  proper 
scrutiny.  The  preservation  of  these  men  from  disease  is 
the  chief  concern  of  the  medical  officer,  miscalled  the 
surgeon."^ 

The  greatest  care  must  be  had  from  the  earliest  moment 
to  control  and  prevent  the  spread  of  infectious  disease  in 
camps,  especially  in  those  of  newly  recruited  or  assembled 
troops.  Many  of  the  men  will  doubtless  be  already 
infected  or  disease  carriers,  and  the  conditions  of  camp 
life  are  especially  favorable  for  the  rapid  dissemination  of 
any   contagion   or   infection   that   may   be   introduced. 


1  Colonel  Woodhull,  loc.  cit. 
30 


466  MILITARY  HYGIENE 

That  this  danger  is  most  serious  is  shown  by  the  records 
of  all  armies,  but  that  it  can  be  obviated  or  markedly 
lessened  by  strict  sanitary  care  and  watchfulness  has 
also  been  demonstrated.  Thus,  in  the  French  Army 
there  were  in  January,  1915,  16,505  cases  and  2268  deaths 
from  acute  contagious  diseases,  while  in  the  correspond- 
ing month  of  1917,  there  were  only  1990  cases  and  41 
deaths.  Much  of  the  illness  in  the  former  month  was 
due  to  typhoid  fever  (13,993  cases  and  2210  deaths)  a  ad 
the  control  of  this  by  inoculation  and  other  sanitary 
measures  rapidly  reduced  the  number  of  cases  to  393  for 
December,  1916,  and  an  average  of  51  per  month  for  the 
first  five  moQths  of  1917. 

The  remarkable  results  and  highly  positive  protection 
against  typhoid  fever  secured  by  the  inoculation  of 
troops  largely  removes  the  menace  of  this  infection  from 
camp  life.  Nevertheless,  it  will  be  well  to  appreciate  the 
potential  dangers  from  this  disease,  as  epitomized  by 
Prof.  Victor  C.  Vaughan,  who  was  one  of  the  board  of 
medical  officers  appointed  by  the  Surgeon-General  of  the 
U.  S.  Army  in  1898  to  "  ascertain  the  causes  of  the  existence 
and  spread  of  typhoid  fever  in  the  national  encampments, 
and  to  suggest  means  of  its  abatement. "^ 

"Every  regiment  in  the  United  States  service  in  1898 
developed  typhoid  fever.  Typhoid  fever  not  only  ap- 
peared in  every  regiment  in  the  service,  but  it  became 
epidemic,  both  in  the  small  encampments  of  not  more  than 
one  regiment,  and  in  the  larger  ones  consisting  of  one  or 
more  corps.  Typhoid  fever  became  epidemic  in  camps 
located  in  the  Northern  as  well  as  those  in  the  Southern 
States;  and  it  is  so  widely  distributed  in  this  country  that 
one  or  more  cases  are  likely  to  appear  in  any  regiment 
within  eight  weeks  after  assembly.  Typhoid  fever  usually 
appears  in  military  expeditions  within  eight  weeks  after 
assembly. 

"With  typhoid  fever  as  widely  disseminated  as  it  is  in 

^  Journal  American  Medical  Association,  June  9,  1900. 


TYPHOID  FEVER  IN  CAMPS  467 

this  country,  the  chances  are  that  if  a  regiment  of  1300 
men  should  be  assembled  in  any  section  and  kept  in  a 
camp  the  sanitary  conditions  of  which  were  perfect,  one 
or  more  cases  of  typhoid  fever  would  develop. 

"Neither  the  miasmatic  theory  nor  the  pythogenic 
theory  of  the  origin  of  typhoid  fever  is  supported  by  the 
investigations,  but  they  confirm  the  doctrine  of  the  specific 
origin  of  typhoid  fever.  It  is  disseminated  by  the  trans- 
ference of  the  excretions  of  an  infected  individual  to  the 
alimentary  canals  of  others,  and  it  is  more  likely  to 
become  epidemic  in  camps  than  in  civil  life,  because  of  the 
greater  difficulty  of  disposing  of  the  excretions  from  the 
human  body.  A  man  infected  with  typhoid  fever  may 
scatter  the  infection  in  every  latrine  of  a  regiment  before 
the  disease  is  recognized  in  himself. 

''Camp  pollution  was  the  greatest  sanitary  sin  com- 
mitted by  the  troops  in  1898,  and  it  may  be  stated  in  a 
general  way  that  the  number  of  cases  of  typhoid  fever  in 
the  different  camps  varied  with  the  method  of  disposing 
of  excretions.  The  tub  system  of  disposal  of  fecal  matter 
as  practised  in  certain  divisions  is  to  be  condemned,  and 
the  regulation  pit  system  is  not  a  satisfactory  system  of 
disposing  of  fecal  matter  in  permanent  camps.  The 
Board  has  recommended  that  in  permanent  camps  where 
water-carriage  cannot  be  secured,  all  fecal  matter  should 
be  disinfected  and  then  carted  away  from  camp. 

"Some  commands  were  unwisely  located,  and  in  some 
instances  the  space  allotted  the  regiments  was  inadequate. 
Many  commands  were  allowed  to  remain  on  one  site  too 
long,  and  requests  for  change  in  location  made  by  medical 
officers  were  not  always  granted.  Greater  authority 
should  be  given  medical  officers  in  matters  relating  to  the 
hygiene  of  camps.  Superior  line  officers  cannot  be  held 
alt6gether  blameless  for  the  insanitary  condition  of  the 
camps. 

"Infected  water  was  not  an  important  factor  in  the 
spread  of  typhoid  fever  in  the  national  encampments  in 
1898.    Flies  undoubtedly  served  as  carriers  of  the  infec- 


468  MILITARY  HYGIENE 

tion;  it  is  probable  that  the  infection  was  disseminated  to 
some  extent  through  air  in  the  form  of  dust;  personal 
contact  was  undoubtedly  one  of  the  means  by  which  it  was 
spread,  and  it  is  more  than  likely  that  men  transported 
infected  material  on  their  persons  and  clothing,  and  thus 
disseminated  the  disease. 

"A  command  badly  infected  with  typhoid  fever  does 
not  lose  the  infection  by  simply  changing  location,  but 
when  it  changes  its  location  it  carries  the  specific  agents 
of  the  disease  in  the  bodies  of  the  men,  in  their  clothing, 
bedding,  and  tentage,  and  even  an  ocean  voyage  does  not 
relieve  an  infected  command  of  its  infection.  However, 
after  a  command  becomes  badly  infected  with  typhoid, 
change  of  location,  together  with  thorough  disinfection  of 
clothing,  bedding,  and  tentage,  is  necessary. 

"Except  in  case  of  most  urgent  military  necessity,  one 
command  should  not  be  located  on  a  site  recently  vacated 
by  another,  but  the  fact  that  a  command  expects  to  change 
its  location  does  not  justify  neglect  of  proper  policing  of 
the  ground  occupied. 

"It  is  desirable  that  soldiers'  beds  should  be  raised 
from  the  ground  and  medical  officers  should  insist  that 
soldiers  remove  their  outer  clothing  at  night  when  the 
exigencies  of  the  situation  permit.  In  some  of  the  en- 
campments the  tents  were  much  too  crowded. 

"  Malaria  was  not  a  prevalent  disease  among  the  troops 
that  remained  in  the  United  States,  and  while  the  inves- 
tigations show  that  coincident  infection  with  malaria  and 
typhoid  fever  may  occur,  the  resulting  complex  of  symp- 
toms does  not  seem  to  be  sufficiently  well  defined  and 
uniform  to  be  recognized  as  a  separate  disease.  The 
continued  fever  that  prevailed  among  the  soldiers  in  this 
country  in  1898  was  typhoid  fever,  but  in  military  prac- 
tice typhoid  is  often  apparently  an  intermittent  disease. 

"About  one-fifth  of  the  soldiers  in  the  national  encamp- 
ments in  the  United  States  in  1898  developed  typhoid 
fever;  army  surgeons  correctly  diagnosed  a  little  less  than 
one-half  the  cases  of  typhoid  fever,  and  while  the  deaths 


TYPHOID  FEVER  IN  CAMPS  469 

from  typhoid  fever  were  more  than  80  per  cent,  of  the 
total  deaths,  the  percentage  of  deaths  among  cases  of 
typhoid  fever  was  about  7.5.  When  a  command  is  thor- 
oughly saturated  with  typhoid  it  is  probable  that  from 
one-third  to  one-quarter  of  the  men  will  be  found  suscep- 
tible to  the  disease. 

"  The  belief  that  errors  in  diet,  with  consequent  gastric 
and  intestinal  catarrh,  induced  typhoid  fever,  or  that 
simple  gastro-intestinal  disturbances  predispose  to  it,  is 
not  supported  by  the  investigations.  More  than  80  per 
cent,  of  the  men  who  developed  typhoid  fever  had  no 
preceding  intestinal  disorder. 

"The  shortest  period  of  incubation  in  typhoid  fever  is 
probably  something  under  eight  days,  and  one  who  has 
lived  in  a  camp  in  which  typhoid  fever  is  prevalent  is 
liable  to  develop  this  disease  any  time  within  eight  weeks 
after  leaving  such  a  camp." 

In  great  contrast  with  this  experience  and  that  of  other 
great  nations  in  earlier  wars,  was  the  record  of  the  Japanese 
army  in  the  Russo-Japanese  war  and  of  our  own  Army 
and  the  armies  of  the  Allies  in  the  great  conflict  just  ended. 
In  spite  of  great  privations,  almost  incredible  exertions, 
and  other  factors  that  favored  the  development  of  typhoid 
fever  and  other  infectious  diseases  in  epidemic  form,  the 
Japanese  Army  remained  almost  entirely  free  from  their 
incidence,  and  the  death-rate  attributable  to  them  was  so 
far  below  that  of  any  previous  experience  of  similar 
nature  as  to  excite  the  surprise  and  admiration  of  the 
professional  world.  And  yet  the  result  was  obtained 
simply  by  making  the  medical  officers  of  the  army 
supreme  in  authority  in  all  matters  pertaining  to  the 
health  of  the  troops  under  their  command,  and  by  the 
practical  obsers^ance  and  carrying  out  of  sanitary  prin- 
ciples already  well  known  in  their  entirety  by  every 
physician  of  intelligence. 

The  inoculation  of  soldiers  and  sailors  against  typhoid 
fever  by  the  subcutaneous  introduction  of  one  or  more 
doses  of  killed   typhoid    and    paratyphoid    bacilli   is   a 


470 


MILITARY  HYGIENE 


comparatively  recent  innovation  in  military  and  naval 
hygiene.  Introduced  practically  and  with  good  results 
by  Sir  Almroth  Wright  in  the  British  Army  in  India  in 
1898,  and  later  in  the  Boer  War  in  Africa,  it  has  had  a 
thorough  testing  in  the  Army  and  Navy  of  the  United 
States.  That  it  is  efficacious  is  indicated  by  the  graphic 
representation  of  Fig.  131  and  by  the  following  quotation 
from  the  Surgeon-GeneraVs  Report  of  1918:  ''If  the 
morbidity  from  typhoid  fever  had  been  as  great  in  the 


RflfTK 


nPHOlP  FEVDR 

flpnission  flnp  dpath  rhtcs 

TOR  CfflJSTtD  ntM  m  THE  U.S.  Fimi  fo  l/S) 

I897-BI7 


lADnissions 

I  DEATHS 


I    11  ^i 


IKL . 


1898 1899 I9D0 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911  1912 1913 1914 1915 1916  1917 


Fig.  13] 


-From  the  report  of  the  Surgeon-General,  U.  S.  Army, 
for  1918. 


Army  during  the  year  1917  as  during  the  Spanish- Ameri- 
can War,  for  each  1,000,000  men  there  would  have  been 
140,000  cases  and  1400  deaths.  Actually,  the  mean 
annual  strength  of  the  Army  was  678,579.  As  it  was, 
there  were  297  cases  and  23  deaths."  .  .  .  "More- 
over, it  was  evident  upon  investigation  that  in  a  large 
proportion  of  these  cases  the  protective  inoculation  of  the 
newly  enlisted  men  had  not  been  completed.  It  cannot 
be  claimed  that  all  our  protection  from  such  a  calamity 


ANTITYPHOID  INOCULATION  471 

is  due  to  vaccination,  as  sanitation  had  much  effect,  but 
enough  cases  are  occurring  in  spite  of  all  precautions  to 
show  that  there  is  constant  danger  of  infection  and 
constant  need  of  protection  by  vaccination." 

Formerly  the  inoculation  against  typhoid  and  para- 
typhoid fevers  was  given  by  three,  separate  injections  at 
intervals  of  about  a  week,  but  "recent  experiments  con- 
ducted at  the  Army  Medical  School  have  resulted  in  the 
perfecting  of  an  oil  vaccine  modelled  after  the  French 
vaccine,  by  which  a  complete  immunization  can  be  given 
in  one  dose.  This  is  a  distinct  practical  advance  as  an 
administrative  measure  as  it  saves  time  and  labor." 
The  person  to  whom  it  is  administered  should  be  in 
good  health  at  the  time,  and  the  temperature  should  be 
taken  in  each  case.  It  is  probable  that  a  marked  reac- 
tion indicates  that  the  individual  was  specially  susceptible 
to  the  infection. 

Despite  the  fact  that  malaria  was  apparently  not  very 
prevalent  among  the  troops  in  this  country  in  the  Spanish- 
American  or  in  the  recent  war,  it  is  a  disease  that  is  often 
vers'  harmful  and  disastrous  to  armies.  So  is  dysentery 
and,  in  other  climates  or  countries,  yellow  fever  and 
cholera.  On  account  of  the  influence  of  the  mosquito 
in  transporting  the  germs  of  malaria,  yellow  fever,  and 
other  diseases,  a  simple  mosquito  bar  or  net  should  be 
included  in  the  kit  of  every  soldier,  especially  of  those 
serving  in  tropical  countries  or  malarial  districts,  and 
the  Surgeon-General's  report  of  1899  gives  evidence  of 
its  efficacy  in  preventing  such  diseases  among  our  soldiers 
in  Cuba.  Other  diseases  that  were  of  grave  importance 
at  one  time  or  another  in  the  recent  conflict  were  typhus 
fever  on  the  eastern  front,  tetanus,  measles,  pneumonia, 
cerebrospinal  meningitis,  trench  fever  and,  in  the  later 
part  of  1918,  epidemic  influenza,  the  mortality  from 
the  latter  disease  in  conjunction  with  pneumonia  being 
excessively  high  in  the  camps  in  this  country-  which  had 
been  relatively  free  of  the  other  diseases. 


472 


MILITARY  HYGIENE 


The  accompanying  table  shows  the  relative  admission 
rate  of  certain  common  diseases  in  the  Army  July  to 
December,  1861,  and  July  to  December,  1917.  Figures 
denote  actual  number  of  cases  of  disease  reported  in 
the  entire  Army  of  white  troops.    As  the  strength  of 


THErRUITSOfFRD/HniVCIIIPinnE 

BY  nmm  use  or-  our  incRCWifiQ  KOOWLWt  of-  ntPicinc  ftnp  — 

JflttlTflTIOrt  SINCt  CIVIL  WflRTirWS  IT  HAS  KtM  POSSIBLE  TO  PREVtffr  HflLF- H  mUlOtl 
CflStS  OP  DIStASt  flnP  5flVC  THt  LIVtS  OP  Tttl  WmBtW  SOLDItRS 


IMTH&riRST  HflLf 


200,00- 


150,000- 


SO,  OOP  s.tf  /.>.w^/ 


3P,0ffP. 


10,000 . 


"itKR.  Of  MOBIUMTlOft 


CIVIL  LIBBWY 
WAR    WAR 


Fig.  132, — From  the  Report  of  the  Surgeon-General,  U.  S.  Army, 
for  1918. 

the  Army  in  1917  was  about  three  times  that  of  the 
Army  of  1861,  the  actual  number  of  cases  in  1861  has 
been  multiplied  by  three. 

"This  table,  represented  graphically  in  Fig  132,  speaks 
for  itself.  Aside  from  gonococcus  infection  (which  is 
probably  commoner  now  than  formerly,  and  is  almost 
certainly  more  carefully  diagnosed)  none  of  the  diseases 
of  the  list  show  an  important  increase  over  1861 .    Measles 


MORBIDITY  IN  THE  CIVIL  AND  WORLD  WARS     473 

and  mumps  ap})areiitly  show  a  slight  increase.  The 
great  reductions  in  disease  are  those  brought  about  by 
improved  sanitation.  Diarrhea  and  dysentery  are  reduced 
from  244,(X)()  to  11,000,  due  to  treatment  of  feces  and 
fighting  the  fly.  Typhoid  fever  is  reduced  from  10,000 
to  225  by  keeping  down  the  fly  and  especially  by  pro- 
tective inoculation;  typhoid,  the  former  great  scourge  of 
armies,  has  become  as  negligible  as  smallpox.  Malaria 
has  been  reduced  from  167,000  to  less  than  2000,  due  to 
elimination  of  mosquito  breeding  areas. 

,       ADMISSIONS,  FIRST  SIX  MONTHS  CIVIL  WAR  AND 
PRESENT  WAR  COMPARED  (WHITE  TROOPS). 

United  States 

enlisted  men, 

First  half-      July-Dec, 

year  of        1918  (first 

Civil       half-year  of 

Disease.  WarXS.    present  war). 

Measles 41,815  46,428 

Pneumonia 9,246  7,675 

Mouth  and  throat  infections      ....  125,445  52,462 

Mumps 6,336  7,843 

Typhoid  fever 10,068  225 

Minor  intestinal  inflammation  .      .      .      .  244,107  10,985 

Malaria 167,163  1,796 

Tuberculosis  and  hemorrhage  of  lungs      .  7,998  6,850 

Syphilis 14.790  7,755 

Gonococcus  infection 18,849  45,027 

Total 645,817       187,046 

"Mouth  and  throat  infections  have  been  cut  in  third 
by  better  ventilation,  preventing  of  crowding  and  spitting, 
and  the  isolation  of  carriers.  The  result  for  the  various 
diseases  amounts  to  a  saving  during  this  half  year  of 
mobilization  of  about  half  a  million  cases  of  sickness  and 
the  rescuing  of  the  lives  of  10,000  soldiers.  Of  deaths 
in  1917  there  were  2984  in  Army  enlisted  men  in  the 
United  States.  For  the  same  strength  in  the  Civil  War 
there  were  13,959.  Thus  the  advance  in  sanitation  and 
preventive  medicine  since  1861  has  saved  in  the  first  half 
year  of  the  war  over  10,000  lives." 

As  typhoid  fever,  dysentery  and  cholera  are  well  known 
to  be  transmitted  by  drinking-water,  sanitary  precautions 

*  Report  of  the  Surgeon-General,  U.  S.  Army,  for  1918. 


474  MILITARY  HYGIENE 

as  to  the  care  of  the  water  must  be  observed.  Though 
the  quotation  above  states  that  "infected  water  was  not 
an  important  factor  in  the  spread  of  typhoid  fever,  etc./' 
it  must  not  be  inferred  that  no  cases  were  found  to  be 
due  to  such  water.  In  fact,  many  cases  were  undoubtedly 
thus  caused,  as  Vaughan  clearly  states;  but  the  authorities, 
early  realizing  the  dangers  that  might  be  due  to  a  bad 
water,  made  such  efforts  to  obtain  pure  supplies  that  other 
means  of  infection  became  relatively  more  important. 
Every  effort  should  therefore  be  made  to  secure  the 
purest  water-supply  possible  in  every  military  camp, 
and  to  have  it  thoroughly  sterilized  before  use  if  there 
is  any  suspicion  of  its  pollution.  A  full  description  of 
filtration  methods  and  of  the  sterilizer  (Forbes,  p.  209) 
that  was  adopted  by  the  Army  has  been  given  in  the 
chapter  on  Water. 

The  Darnall  Filter. — Should  the  Lyster  bag  not  be 
available  this  apparatus  may  be  used.  This  is  an  adapta- 
tion of  the  principle  of  mechanical  filtration  to  the  needs 
of  troops  in  the  field.  It  consists  of  a  galvanized  iron  tank, 
two  water  cans,  and  a  siphon  filter  and  cloth  crated.  The 
essential  part  is  the  cylindrical  metal  framework  of  the 
siphon,  over  which  is  wrapped  the  filtering  material,  a 
closely  woven  cotton  fabric.  This  is  placed  in  the  tank 
filled  with  raw  water  to  w^hich  the  precipitant  has  already 
been  added,  and  the  water  after  passing  through  the 
filtering  cloth  into  the  cylinder  is  discharged  by  siphonage 
into  the  water  can.  As  matters  in  suspension  deposit 
upon  the  cloth  the  flow  diminishes,  and  the  filter  should 
be  taken  out  and  the  cloth  removed  and  cleaned  by  wash- 
ing and  sterilizing  by  boiling  water.  The  precipitant  con- 
sists of  alum  and  sodium  carbonate  in  such  proportions 
that  they  neutralize  each  other.  This  precipitant  is 
furnished  in  a  small  tin  can  with  a  measure  which  holds 
2  grams.  The  water  cans  when  filled  to  the  mark  hold  3 
gallons.  One  measure  of  the  precipitant  added  to  each  can 
of  raw  water  is  sufficient  for  even  grossly  polluted  waters. 

The  crated  filter  weighs  52  pounds  and  will  deliver  about 


DRINKING-WATER  AND  FOOD 


475 


200  gallons  of  water  iji  four  hours.  It  completely  clarifies 
the  water,  and  its  bacterial  efficiency  is  about  98  per  cent. 
This  apparatus  cannot  be  depended  upon  for  the  certain 
elimination  of  all  pathogenic  bacteria,  but  it  jjurifies 
or  linary  waters  to  a  degree  that  renders  them  reasonably 
safe.  It  wil)  furnish  plenty  of  clear  water  unchanged  in 
temperature  and  taste  within  an  hour  after  getting  into 
camp.  One  filter  may  be  carried  by  each  company  in  the 
field. 

For  troops  in  the  field  and  where  water  of  reasonable 
clarity  can  be  had,  the  so-called  Lyster  bag  has  come 


Fig.  133. — Tripods  for  Lyster  bags,  with  one  bag  partly  svispended  from 
foremost  tripod. 

into  recent  use.  This  is  made  of  heavy  canvas  with 
several  closing  push-cocks  near  the  bottom,  holds  about 
40  gallons,  has  a  removable  canvas  cover  to  exclude  dust 
and  dirt  and  can  be  slung  from  any  convenient  support 
by  means  of  rope  loops  at  the  top.  When  hung  and 
filled,  a  sealed  tube  containing  1  gram  of  fresh  calcium 
hypochlorite  is  broken  and  its  contents  dissolved  in  the 
water,  thus  quickly  sterilizing  it.    Any  perceptible  taste 


476 


MILITARY  HYGIENE 


of  chlorine  which  is  in  the  strength  of  approximately  1 
part  per  1,000,000  soon  disappears.  Evaporation  of  water 
that  oozes  through  the  canvas  also  tends  to  cool  the 
contents.  When  empty,  the  bag  weighs  comparatively 
little  and  takes  up  almost  no  space  in  transportation. 

/^  As  the  efficiency  of  the  soldier  depends  so  much  upon 
his  food,  and  as  it  is  of  importance  for  so  many  different 
reasons,  it  is  not  strange  that  it  has  been  the  subject  of 
the  most  careful  investigation.     In  fact,  much  of  the 


Fig.  134. — Lyster  bag  supported  by  stacked  filters.     (Ford.) 

scientific  knowledge  now  pertaining  to  dietetics  is  the 
result  of  the  work  of  the  various  governments  in  their 
efforts  to  determine  the  most  satisfactory  and  efficient 
military  rations.  Considering  the  men  simply  as 
machines,  true  economy  requires  that  their  food  shall 
be  ample  in  quantity  and  good  in  quality.  Attention 
must  also  be  given  to  its  transportation  and  prepa- 
ration, and  to  its  character  as  a  source  of  heat  and 
energy. 

A  study  of  the  standard  daily  rations  of  the  various 
armies  of  the  world  at  once  shows  a  noticeable  uniformity 


DRINKING-WATER  AND  FOOD  477 

among  them  in  the  amounts  and  relative  proportion  of 
the  food-principles  and  in  the  ratio  of  nitrogen  and  carbon. 
And  as  these  have  all  had  the  test  of  long  time  and  exten- 
sive experience,  they  serve  to  establish  their  own  scientific 
accuracy,  as  well  as  that  of  the  dietetic  ratios  which 
have  been  determined  in  other  ways  and  to  which  they 
so  closely  correspond. 


Fig.  135. — Wheeled  field  kitchen,  with  acconipauyiuK  supply  wagon. 
In  addition  to  the  ovens,  the  kitchen  has  a  large  kettle  for  soup  and  a 
smaller  one  for  coffee  let  in  at  the  top. 


No  part  of  a  military  administration  is  of  more  im- 
portance than  the  commissary  department,  for  an  army 
without  food  is  soon  worse  than  useless.  But  it  is  not  easy 
to  feed  properly  large  numbers  of  men  in  an  active  cam- 
paign when  the  whole  body  is  moving  rapidly  from  place 
to  place  and  when  the  exigencies  of  the  day  may  seem  to 
require  all  available  means  of  transportation  for  other 
purposes.  Consequently,  much  effort  has  been  made  to 
supply  rations  that  are  condensed  in  bulk  and  that  require 
as  little  immediate  preparation  as  possible. 

Considerable  advance  in  this  line  has  been  made  in 
recent  years,  and  various  soups,  meats,  and  vegetables, 


478  MILITARY  HYGIENE 

condensed  and  ready-cooked,  are  now  often  supplied  when 
the  same  cannot  be  had  in  a  fresh  state.  That  such  may 
be  entirely  satisfactory  cannot  be  denied,  but  those  in 
authority  must  be  especially  careful  as  to  certain  points, 
viz.,  that  the  food  is  not  lacking  in  quality  and  that  the 
processes  employed  have  not  impaired  its  dietetic  value  or 
digestibility  nor  permitted  harmful  changes  to  take  place 
in  it.  The  temptations  of  the  army  contractor  are  often 
hard  to  withstand;  moreover,  tests  have  shown  that  if 
concentration  be  carried  too  far,  not  only  the  digestibility, 
but  the  nutritive  value  as  well  of  the  food  may  be  seriously 
impaired.  Thus  the  valuable  salts  and  vitamines  may  be 
lost  with  the  water  in  the  compression  of  vegetables. 
Again,  the  processes  may  make  the  foods  too  uniform 
in  taste,  or  there  may  be  the  omission  of  such  accessories 
as  vinegar,  spices,  etc.,  or  there  may  be  ignorance  as  to 
how  to  cook  them  properly;  and  it  must  always  be 
remembered  that  palatability  has  much  to  do  with 
digestibility.  For  these  reasons  it  will  be  wise  to  have 
at  least  part  of  the  food  issued  in  as  nearly  the  fresh  or 
ordinary   state   as   possible. 

Space  does  not  permit  the  consideration  of  the  various 
articles  of  food  composing  the  prescribed  ration,  but  it  is 
evident  that  the  laws  of  dietetics  govern  here  as  elsewhere. 
It  may  be  well  to  say,  however,  that  experience  seems  to 
show  that  alcohol  should  not  be  included  in  the  regular 
ration,  but  should  only  be  issued,  if  at  all,  in  certain 
exigencies  and  in  small  quantities.  At  present  it  is  even 
omitted  from  the  outfit  and  stock  of  field  hospitals  and 
ambulance  companies. 

/Regular  and  thorough  inspection  must  be  made  not 
only  of  the  food  supplied  to  the  troops,  but  of  kitchens, 
mess-halls,  store-rooms,  warehouses,  canteens,  etc.,  in 
order  that  these  may  be  kept  in  a  sanitary  and  safe 
condition  at  all  times.  Particular  care  must  be  taken  to 
exclude  flies  as  well  as  other  vermin,  as  these  may  be,  as 
they  have  been  in  the  past,  the  carriers  of  typhoid  and  other 
infections  to  the  food  of  the  men.     Likewise,  all  cooks. 


THE  CLOTHING  OF  THE  SOLDIER 


479 


handlers  of  food  and  attendants  at  canteens  should  be 
examined  in  order  to  excKide  typhoid  and  other  "  carriers," 
and  prevent  the  consequent  risk  to  those  whom  they 
serve. 

The  same  principles  hold  good  in  regard  to  soldiers' 
clothing  as  for  that  of  other  people,  but  "  in  selecting  the 
material  the  chief  points  to  be  considered  are  its  permea- 
bility, durability,  and  the  property  it  has  of  conducting 
and  absorbing  heat."    It  would  be  well  if  the  undergar- 


FiG.  136. — Wheeled  field  kitchen  in  service. 


ments  were  always,  in  part  at  least,  of  wool.  The  material 
of  the  uniforms  and  its  weight  should  depend  upon  the 
exigencies  of  the  service,  considering  both  the  locality 
and  the  season  of  the  year.  In  cold  weather  wool  should, 
of  course,  have  first  place;  in  hot  climates  the  stout  cotton 
fabric  called  khaki  seems  to  meet  the  conditions  most  satis- 
factorily. "The  color  of  the  material  has  an  important 
bearing  on  the  hygienic  value  of  the  clothing,  and  in 
regard  to  the  absorption  of  heat  exerts  more  influence 


480 


MILITARY  HYGIENE 


than  the  material  itself.  .  .  .  White  possesses  very  slight 
absorptive  power  compared  to  other  colors,  and,  next  to 
this  in  the  scale,  gray  or  pale  yellow  gives  the  best  results. 
Gray  is  the  best  color  for  soldiers'  dress  on  service,* for 
white  is  least  suited  to  the  field,  as  it  soils  so  quickly. 
The  khaki  drill  corresponds  very  closely  with  gray  as 
regards  absorption  power.  "^ 


Fig,  137. — Portable  camp  stove  on  brick  foundation.     Mess-hall  and 
kitchen  in  rear  vestibuled  and  screened  to  exclude  flies. 


.  The  clothing  should  nowhere  be  so  tight  as  to  interfere 
with  respiration  or  circulation  or  with  free  movement  of 
the  body.  There  should  be  a  sufficiency  of  socks  in  each 
man's  kit,  for  "a  good  sock  kept  clean,  is  a  protective 
against  sore  feet."  Boots  or  shoes  should  be  comfortable 
as  well  as  durable  and  water-proof.  Leggings  may  often 
be  used  to  advantage ;  they  may  be  of  stout  canvas,  khaki, 
or  leather.  Helmets  or  other  head-dress  should  be  light 
and  well  ventilated,  and  of  a  non-absorbent  color.     Ab- 

1  Notter  and  Firth,  p.  955. 


DISPOSAL  OF  CAMP  WASTES  481 

dominal  bands  of  flannel  are  excellent  protectives  against 
digestive  disturbances,  if  the  men  can  be  induced  to  wear 
them.  Each  kit  should  contain  a  rubber  or  water-proof 
blanket  or  "poncho"  to  protect  the  soldier  from  the 
dampness  of  the  ground  at  night;  it  can  also  be  used  as  a 
cape  in  rainy  weather.  The  weight  of  the  kit,  arms, 
accoutrement,  etc.,  is  often  excessive,  and  should  be  kept 
as  light  as  possible.  In  some  armies  as  much  as  seventy 
pounds  is  to  be  carried  by  each  soldier.  It  should  be  so 
divided  that,  when  on  the  march,  as  much  of  this  as 
possible  can,  and  should,  be  carried  in  wagons  for  the  men, 
they  retaining  only  their  arms  and  water  bottles.  "  Weights 
are  most  easily  borne  when  the  following  points  are 
attended  to:  (1)  They  must  be  as  near  the  centre  of 
gravity  as  possible.  (2)  The  weights  must  in  no  case 
compress  the  lungs,  or  interfere  with  the  respiratory 
movements  or  the  elimination  of  carbon  dioxide,  or  hinder 
the  transmission  of  blood  through  the  lungs,  or  render 
difficult  the  action  of  the  heart.  (3)  No  important  muscles, 
vessels,  or  nerves  should  be  pressed  upon.  (4)  The  weights 
should  be  distributed  as  much  as  possible  over  several 
parts  of  the  body."^ 

The  last  statement  means  that  the  pressure  will  be  most 
advantageously  put  upon  the  tops  of  the  shoulder-blades 
and  upon  the  hip-bones  and  sacrum. 

The  possibility  of  the  transmission  of  typhus  and 
trench  fevers  and  probably  other  infections  by  means  of 
lice  and  other  vermin  render  imperative  the  provision, 
when  possible,  of  well-equipped  stations  for  freeing  both 
the  man  and  his  clothing  of  such  infestation.  Such 
delousing  stations  become  an  esential  feature  of  quaran- 
tine in  preventing  the  introduction  of  the  diseases  in 
question  and  their  "carriers"  into  the  country-. 

The  disposal  of  the  wastes  of  a  camp  constitutes  one  of 
its  gravest  problems.  If  it  is  a  permanent  post  and  the 
men  are  quartered  in  barracks  with  a  sufficient  water- 

»  Notter  and  Firth,  pp.  961  anrl  962. 
31 


482 


MILITARY  HYGIENE 


supply,  it  may  be  best  to  construct  a  complete  sewage 
and  sewage-disposal  system;  but  where  the  encampment 
is  temporary  the  difficulties  are  greatly  increased.  Even 
though  the  camp  is  strictly  policed,  as  it  always  should 
be,  and  the  garbage  and  similar  wastes  destroyed  by 
fire  or  burial,  there  remains  the  disposal  of  the  excreta 
of  large  numbers  of  men,  which,  if  neglected,  is  almost 
certain  to  become  a  source  of  infection. 


Fig.  138. — Garbage  incinerator,  with  central  pyramid  to  increase 
draught. 

The  customary  sinks  are  not  only  likely  to  pollute 
the  ground-water  and  perhaps  the  water-supply  of  the 
camp,  but  they  are  also  a  constant  offense  to  the  senses, 
and  we  now  know  that  infection  may  be  carried  by 
flies  directly  from  them  to  the  food  in  the  kitchens  and 
mess- tents.  Where  used,  their  contents  should  be  cov- 
ered twice  or  thrice  daily  with  a  layer  of  fresh  earth, 
lime  or  oil,  and  when  the  contents  reach  within  two  feet 
of  the  surface  they  should  be  filled  with  earth  and  new 
ones  opened.  At  times,  instead  of  using  earth  or  lime 
for  a  covering,  dry  grass  or  straw  may  be  spread  over 


DISPOSAL  OF  CAMP  WASTES  483 

the  contents  and  burned  two  or  three  times  a  day-  This 
not  only  serves  to  disinfect  the  surface  and  sides  of  the 
trench  by  fire,  but  the  ashes  of  the  straw  form  a  loose 
covering  of  several  inches'  thickness  which  completely 
conceals  the  subsequent  additions  and  at  the  same  time 
effectually  protects  all  the  contents  from  the  access  of 
flies.  Colonel  WoodhuU  suggests  the  burning  twice 
a  day  of  small  quantities  of  petroleum  poured  on  the 
surface  of  the  contents  of  the  sink.  If  the  sinks  are 
primarily  dug  to  the  depth  of  several  feet,  this  burning 
of  straw  and  oil  may  be  done  without  risk  of  igniting 
the  seats,  moreover;  if  the  seats  are  made  like  inverted 
boxes  completely  covering  the  sinks,  and  if  the  interior 
of  these  boxes  and  the  sides  and  ends  of  the  sinks  are 
well  sprayed  with  a  mixture  of  lamp  black  and  crude  oil, 
the  interior  is  made  so  dark  as  to  be  almost  completely 
shunned  by  flies,  and  one  burning  a  day  will  be  sufficient. 

However,  it  will  often  be  wiser  to  do  away  with  sinks 
altogether  and  to  provide  measures  whereby  the  excreta 
can  be  at  once  chemically  disinfected  and  then  removed 
beyond  the  limits  of  the  camp.  Theoretically,  the  tub  or 
pail  system  would  seem  to  be  available  if  proper  dis- 
cipline and  supervision  could  be  had;  but  practical 
experience  in  certain  camps  rather  proves  it  to  be  unsatis- 
factory. Unless  the  contents  are  disinfected  immediately, 
the  soil  about  the  camp  will  be  almost  certainly  polluted 
and  infected  when  the  receptacles  are  removed  for  empty- 
ing, and  the  flies  will  also  be  as  numerous  as  at  the  sinks. 
If  the  tubs  should  be  partially  filled  with  a  disinfectant 
before  use,  and  if  they  should  have  close-fitting  covers 
which  would  only  be  removed  at  the  time  of  use,  the 
objections  to  them  would  be  diminished,  but  would  still 
remain  in  part. 

At  the  time  of  the  Spanish-American  War  the  board 
of  medical  officers  already  referred  to  recommended,  and 
the  Surgeon-General  and  Adjutant-General  adopted  the 
recommendation,  that  the  excreta  be  received  into  a 
large   galvanized   iron   trough   partially   filled   with   an 


484 


MILITARY  HYGIENE 


active  disinfectant  solution,  preferably  milk  of  lime  on 
account  of  its  combined  efficiency  and  cheapness.  The 
trough  was  to  be  located  in  a  suitable  building,  and  when 
full  or  at  regular  intervals  was  to  be  emptied  by  means 


BACK  SAME -HEIGHT 


HANDLE  BLOCKS 
2"X  4" 

2"x  4"acting  as 

LEGS  WHEN  BOX 
TURNED  OVER 


BRACES  2 
INSIDE  BOX 


LEATHER 
STRAP  HINGES 


X  4  STRIP  INSIDE 
ON  WHICH  BOX  SETS 
MAKING  IT  FLY  PROOF 


Fig. 


139. — ^Latrine  box  used  in  the  camps  at  Columbus  and  elsewhere. 
(Lewis  and  Miller.) 


GROUND  AVAILABLE  FOR  TURNING 
BOX  BACKWARD  IN  BURNING  PIT 

1 

a 

URINAL 

1 
i 

i 

LATRINE  BOX 

SCREEN 

rm 

L_l                              1—1 

V7X          nnoR         V7A 

Fig. 


140. — Ground  plan  of  latrine  box,  latrine,  screen  and  urinal   can 
used  at  Columbus  and  elsewhere.     (Lewis  and  Miller.) 


of  a  pumping  cylinder  into  a  large  water-tight  tank  on  a 
wagon,  similar  to  those  of  the  ordinary  odorless  excavat- 
ing apparatus.  It  is  probable  that  such  apparatus  under 
proper  supervision  would  prove  as  efficient  and  practic- 


DISPOSAL  OF  CAMP  WASTES  485 

able  as  any  that  can  be  devised  short  of  a  well-constructed 
system  of  sewers  involving  water-carriage,  the  installa- 
tion of  which  is  obviously  not  feasible  in  a  temporary 
camp  or  in  one  not  having  an  abundant  water-supply, 
but  the  author  has  no  information  that  any  such  methods 
or  apparatus  were  in  use  in  the  service  abroad  or  even  in 
any  of  the  concentration  or  training  camps  in  this  country. 

Provision  should  also  be  made  for  the  disposal  of 
garbage  from  the  kitchens  and  other  refuse  of  the  camp. 
This  can  be  readily  done  where  fuel  is  abundant,  by 
building  a  rough  fireplace  of  stones  in  which  a  fire  is  kept 
burning.  Garbage  thrown  inside  against  the  hot  stones 
quickly  dries  and  bums  without  nuisance.  The  portable 
incinerators  that  have  been  devised  for  disposing  of 
camp  wastes  are  heavy  and  difficult  of  transportation, 
and  so  more  suitable  for  permanent  camps. 

Because  of  its  content  of  grease  and  small  particles 
of  organic  matter  and  its  excessive  volume,  the  used  dish- 
or  "sullage"  water  is  often  difficult  to  dispose  of  and 
capable  of  causing  much  offense  to  the  senses,  especially 
in  a  large  camp  in  warm  weather  and  where  there  is  no 
sewerage.  Evaporation  is  slow  and  wasteful  of  fuel,  but 
may  be  the  most  satisfactory  method  of  disposal.  If 
time  and  conditions  of  soil  are  favorable  for  digging  some 
form  of  septic  tank  or  filtration  might  be  tried,  but  the 
greasy  residue  does  not  yield  readily  to  bacterial  action, 
either  aerobic  or  anaerobic,  and  the  unpleasant  odor  is 
apt  to  attract  flies  and  lead  to  their  multiplication  in  the 
solid  residue,  unless  this  be  burned  over  or  worked  under 
the  surface  of  the  ground. 

Garbage  must  be  kept  well  covered  and  screened  from 
flies  until  finally  disposed  of;  the  area  about  kitchens, 
mess-halls  and  barracks  or  encampments  must  be  thor- 
oughly policed  at  all  times.  On  account  of  its  value  as 
a  food  for  domestic  animals,  the  garbage  may  often  be 
disposed  of  to  persons  living  ia  the  vicinity  of  permanent 
camps  but  only  the  strictest  of  regulations  and  alert 
vigilance  will  prevent  camp  nuisance  and  pollution. 


486  MILITARY  HYGIENE 

In  any  but  a  temporary  camp,  the  feces  of  the  horses 
should  be  removed  to  a  considerable  distance  from  the  camp 
or  else  treated  with  lime  to  prevent  the  breeding  of  flies. 

Space  does  not  permit  of  a  full  discussion  of  military 
hospitals.  At  permanent  posts  they  may  have  almost  all 
the  equipment  and  conveniences  of  the  best  city  hospitals, 
but  in  the  field  in  actual  service  much  must  be  foregone. 
This  often  leads  to  censure  from  the  uninformed  and 
where  censure  is  not  deserved.  But  commanding  officers, 
especially  of  the  medical  service,  should  foresee  every 
emergency  and  provide  for  it  as  far  as  possible,  overrating 
rather  than  underrating  the  probable  needs  and  demands 
upon  the  hospital  staff,  and  providing  for  the  comfort  as 
well  as  the  necessities  of  the  sick  and  wounded.  The 
knowledge  that  typhoid  fever,  for  instance,  is  almost 
certain  to  occur  and  become  epidemic  in  any  camp  of 
considerable  extent  or  duration  in  which  the  men  have 
not  been  protected  by  antityphoid  inoculation  should 
compel  preparation  for  the  proper  treatment  of  this 
disease  in  so  far  as  this  is  possible  in  a  field  hospital.  So 
also,  epidemics  of  such  diseases  as  measles,  cerebrospinal 
meningitis,  influenza  or  pneumonia  may  occur  at  any  time 
and  should  be  anticipated  by  like  preparation  and  foresight. 
The  trained  nurse  has  proved  her  value  in  army  hospital 
work,  and  now  has  a  place  in  the  regular  army  medical 
service.  The  enlistment  and  training  of  a  sufficient  number 
of  hospital  stewards  is  also  of  great  importance,  as  is 
also  the  instruction  of  the  soldiers  themselves  as  to  the 
care  of  themselves  in  emergencies.  Undoubtedly  this 
latter  instruction,  meagre  as  it  was,  and  the  "first-aid, 
packets"  with  which  each  man  was  supplied,  greatly 
contributed  to  the  excellence  of  results  among  the  regular 
troops  in  the  Spanish-American  war,  and  even  more  so 
in  the  late  war. 

A  thorough  course  in  the  fundamental  principles  of 
hygiene  should  be  a  part  of  the  education  of  every  soldier 
in  the  regular  army  and  navy,  and  especially  should  this 
subject  be  established  as  one  of  the  most  important  in 


INSTRUCTION  IN  HYGIENE 


487 


Fig.  141. — Hospital  tent,  with  wall  furled  for  free  ventilation. 


Fi<i.  142. — Field  hospital:    tent  walls  furled  for  free  ventilation. 


Fiu.  143.  "Makinj;  biuth  in  large  galvanized  cans  on  field  stove  for 
hospital  patients. 


488 


MILITARY  HYGIENE 


the  curriculum  at  West  Point  and  Annapolis.  If  the 
graduates  and  future  officers  from  these  great  schools 
are  so  instructed,  it  is  more  than  probable  that  the 
advice  and  suggestions  of  the  medical  officers  of  the 
service  will  be  more  often  accepted  and  enforced  in 
the  future  than  they  have  been  in  the  past. 

Hospital  tents  are  apt  to  be  poorly  ventilated  and 
oppressive  in  hot  weather  or  climates.  They  should  have 
every  advantage  of  location,  that  the  comfort  as  well  as 


Fig.  144. — Officer's  tent,  with  additional  fly  and  showing  mosquito  bar 
in  place  over  cot.     This  is  essentially  a  Munson  tent. 

the  health  of  the  patients  may  be  conserved.  A  venti-: 
lated  hospital  tent,  devised  by  General  E.  L.  Munson, 
M.D.,  U.  S.  A.,  has  been  adopted  by  the  Board  of  Equip- 
ment on  account  of  its  advantages,  chief  of  which  are 
a  better  ventilation  and  a  lowering  of  the  temperature 
within  to  the  extent  of  several  degrees. 

Another  valuable  addition  to  the  hospital  service  of  the 
army  for  the  purpose  has  been  the  purchase  and  thorough 
equipment  of  several  hospital  ships.  The  saving  of  life 
and  alleviation  of  distress  made  possible  by  these  vessels, 


HOSPITAL  TENTS 


489 


Fig.    145. — Pyramidal  touts:    those  iu  the  hack-inrnml  coniplftrly  furled 
to  admit  sunshine  to  all  parts  of  the  covered  area. 


Fig.    146. — A  semipermanent  camp  for  cold  wiMiiur.      1  enta  furled  at 
midday  for  sunlight  and  ventilation. 


490 


MILITARY  HYGIENE 


Fig.  147. — Pyramidal  tent.     (Harrington.) 


i^JK* /^^^^H^BBHi^^^^ 

k  . 

'  ,^|^^'%^>^^^^^H 

k 

'    .^^H^H^^s^^ 

,^^^^^^^x 

y^fflB^''                                                      --1k9^ 

1^^ 

Fig.  148. — Munson  hospital  tent  with  fly.     (Harrington.) 


DUTIES  OF  THE  MEDICAL  OFFICER  491 

when  compared  with  the  effects  of  conditions  obtaining  in 
the  ordinary  transport  ships,  are  incalculable. 

The  work  of  the  soldier,  while  excessive  at  times, 
ordinarily  permits  much  leisure  to  the  men,  which,  in 
turn,  is  conducive  not  only  to  attacks  of  hor^esickness 
and  ennui,  but  to  the  development  of  injudicious  and 
injurious  habits.  Consequently,  anything  that  will 
profitably  employ  the  attention  and  activities  of  the  men 


Fig.  149. — Tents  for  winter  quarters:    furled  at  midday  to  admit 
sunshine. 


when  off  duty  is  beneficial.  For  this  purpose  reading- 
rooms,  athletic  sports,  and  the  work  of  various  trades 
may  be  mentioned.  This  need  furnishes  one  of  the  strong 
arguments  for  the  restoration  and  continuation  of  the  army 
canteen,  or  soldiers'  club.  This  question  involves  the 
treating  "with  human  nature  as  it  exists  in  the  army, 
rather  than  attempting  the  attainment  of  impossible 
ideals,"  and  it  certainly  seems  that  the  favorable  reports 
and  commendation  of  the  very  great  majority  of  army 


492  MILITARY  HYGIENE 

officers  who  have  expressed  their  opinions  concerning  it, 
should  warrant  the  continuance  of  the  canteen-.  At  any 
rate,  the  abiUty  to  keep  his  men  pleasantly  and  advantage- 
ously occupied  is  one  of  the  qualities  of  a  good  com- 
mander, and  medical  officers  should  assist  the  latter  in  this 
respect  whenever  possible. 

The  medical  officer  will  also  be  watchful  to  guard 
against  the  causes  of  the  diseases  which  are  most  preva- 
lent in  the  army,  viz.,  phthisis,  heart  disease,  pulmonary 
diseases,  typhoid,  malaria  and  continued  fevers,  and,  not 
least  in  importance,  venereal  diseases.  The  latter  do 
much  harm  in  most  standing  armies,  and  it  is  as  a  pro- 
phylactic to  these  that  the  occupation  of  time  and  energy 
,  referred  to  above  is  especially  advantageous.  That  the 
incidence  of  venereal  diseases  among  soldiers,  and  presum- 
ably among  others,  may  be  markedly  controlled  by  the 
combined  influence  of  well-ordered  physical  exercise,  per- 
sonal education,  agreeable  recreation,  wholesome  enter- 
tainment, prophylaxis  and  effective  disciplinary  measures 
is  demonstrated  by  the  remarkable  record  of  the  American 
Army  throughout  the  recent  war,  and  much  of  'he  good 
results  achieved  is  undoubtedly  to  be  attributed  to  the 
extraordinary  efforts  that  were  made  to  eliminate  oppor- 
tunity of  temptation  by  keeping  the  men  agreeably  and 
properly  occupied  when  not  on  duty. 

So,  also,  must  the  chief  surgeon  and  his  assistants  keep 
oversight  of  the  rations,  water-supplies,  etc.  They  must  in- 
spect the  men  at  regular  intervals,  weighing  and  measuring 
them,  and  examining  for  heart-strain  or  other  circulatory 
disturbance;  they  must  select  suitable  places  of  encamp- 
ment when  on  the  march,  caring  for  those  who  are  over- 
come by  the  heat  or  exhausted;  they  must  see  that  the 
troops  do  not  injudiciously  expose  themselves  when  over- 
heated; in  fact,  they  must  be  fully  as  zealous  and  active 
as  the  commanding  officer  to  maintain  the  entire  com- 
mand in  its  highest  physical  efficiency. 

The  chief  features  of  naval  as  distinguished  from 
military  hygiene  are  such  as  pertain  to  overcrowding. 


NAVAL  HYGIENE  493 

bad  ventilation  and  excessive  dampness  in  sleeping 
quarters,  excessive  heat  in  engine-rooms  and  stoke-holds, 
exposure  to  inclement  weather,  increased  liability  to  tuber- 
culosis, rheumatism  and  diseases  epidemic  in  foreign 
ports,  such  as  cholera,  yellow  fever,  and  plague,  and  lack 
of  fresh  water,  meats,  and  vegetables,  with  consequent 
increase  in  liability  to  scurvy. 

The  general  principles  of  hygiene,  however,  apply 
on  ship-board  as  elsewhere  and  are  to  be  observed  to 
the  fullest  extent  possible.  For  obvious  reasons,  cleanli- 
ness in  every  detail  should  be  required  by  medical  and 
other  officers  both  as  to  the  vessel  and  the  men  them- 
selves, and  disinfection  should  also  be  resorted  to  whenever 
there  is  occasion  or  suspicion  of  its  need.  Crowding  and 
intimacy  of  contact  make  the  outbreak  and  spread  of 
any  infection  a  serious  danger  to  all. 

Lastly,  the  necessity  for  constant  preparedness,  proper 
esprit  de  corps  and  full  strength  against  an  enemy  on 
board  battleships  or  other  naval  vessels  render  the  duty 
of  maintaining  proper  hygienic  conditions  among  the 
men  a  most  serious  one  to  all  who  are  responsible  for  it, 
and  gives  naval  hygiene  a  dignity  and  importance  equal 
to  that  of  the  army. 

For  further  information  on  this  important  subject  the  reader  is  referred 
to  the  article  on  Military  Hygiene  in  the  Reference  Hand-book  of  the 
Medical  Sciences,  by  Colonel  A.  A.  Woodhull,  M.D.,  and  to  the  text- 
books on  the  same  subject  by  General  Edward  L.  Munson  and  Havard, 
Ashburn  and  Keefer,  each  of  these  being  in  its  way  excellent  and  having 
the  authority  of  practical  experience.  Likewise,  Gatewood's  and  Pryor's 
text-books  on  Naval  Hygiene  will  supply  much  authoritative  data  and 
information  relative  to  features  or  problems  peculiar  to  sanitary  admin- 
istration in  the  naval  service  of  the  government. 


CHAPTER  XV. 
VITAL  STATISTICS. 

Science  is  classified  knowledge.  By  arranging  known 
facts  and  units  into  groups,  and  considering  them  from 
different  points  of  view,  we  discover  the  scope  of  a  par- 
ticular science,  and  are  also  led  to  the  discovery  of  new 
facts. 

In  hygiene  it  is  necessary  to  have  this  classification  of 
facts  to  know  what  progress  we  are  making,  for  the  true 
test  of  any  sanitary  procedure  is  its  efficacy  in  preserving 
health  and  preventing  disease,  and  we  cannot  know 
whether  it  is  efficient  or  not  unless  we  tabulate  and  study 
the  results  and  at  the  same  time  eliminate  disturbing 
factors.  In  this  connection  it  is  to  be  noted  that  our 
facts  must  be  accurate  and  derived  from  sufficient  experi- 
ence, and  that  the  disturbing  factors  are  especially  likely 
to  be  numerous. 

It  is  evident  that  we  may  study  disease  by  direct 
observation  at  the  bedside  and  at  the  postmortem  table,  or 
by  experiment;  and  while  our  knowledge  in  the  past  has 
been  gained  principally  by  the  former  method,  we  now, 
since  the  advent  of  modern  bacteriology  and  parasitology, 
may  further  investigate  many  diseases  by  reproducing 
them  in  susceptible  animals.  In  this  way  we  soon  learn 
that  some  diseases  are  much  more  preventable  than 
others,  and  we  endeavor  to  discover  the  respective  causes 
and  predisposing  conditions  of  each  that  we  may  the  more 
readily  estimate  their  effects  and  take  measures  to  restrict 
and  prevent  their  action. 

Our  observations  may  be  of  two  kinds:  (1)  By  noting 
and  comparing  individual  cases,  or  by  following  the  track 
of  a  particular  outbreak  or  epidemic.  (2)  By  observing 
(494) 


STATISTICAL  PRINCIPLES  495 

large  classes  and  groups  of  men,  which  necessitates  a 
record  of  births,  marriages,  diseases,  and  deaths.  The 
consideration  of  such  records  constitutes  the  study  of 
vital  statistics,  ^h-  i>  Obt  imp  »rt  mt  object  of  which  is, 
a.^''    •  '  r      vO  givn  vs-ar  iiig  of  the  undue  increase 

of  Q^  1-  death  presumed  to  be  due  to  preventable 

cause,  a  )  to  indicate  the  localities  in  which  sanitary 

effort  is  J  it  desirable  and  most  likely  to  be  of  use." 
The  reader  w^ill  also  notice  how  the  study  of  vital  statistics 
broadens  out  into  the  science  of  demography — the  study 
of  the  life  of  peoples  and  communities. 

The  importance  of  the  science  of  vital  statistics,  which 
has  been  well  termed  the  "bookkeeping  of  humanity," 
is  appreciated  when  we  realize  that  "it  points  out  where 
and  to  what  extent  disease  and  death  are  on  the  increase, 
and  suggests  therefor  the  inauguration  ,of  combative 
sanitary  effort,  the  efficiency  of  which  it  enables  us  to 
measure.  It  furnishes  the  basis  for  the  study  of  all  the 
various  social  problems  which  affect  increase  and  diminu- 
tion in  numbers."^ 

The  national  census  reports  now  give  statistical  returns 
not  only  for  the  wards  and  other  political  divisions  of 
some  of  our  large  cities,  but  also  for  so-called  "sanitary 
districts,"  in  which  the  population  is  chiefly  made  up  of 
those  of  marked  racial  or  other  characteristics  that 
influence  the  vital  problem.  The  study  of  such  returns 
supplies  much  information  and  the  explanation  of  many 
otherwise  obscure  phenomena  in  the  vital  statistics  of  a 
municipality. 

At  this  point  it  will  be  well  to  note  certain  elementary 
principles  which  must  be  observed  in  any  statistical 
inquiry,  in  order  that  the  results  of  that  inquiry  may 
have  any  value  whatever.    These  are: 

1.  Our  facts,  or  numerical  units ,  must  have  precise, 
definite,  and  constant  characteristics.  For  example,  in 
determining  the  death-rate  or  sick-rate  from  typhoid  fever, 

'  Harrington  and  Richardson,  Practical  Hygiene,  p.  879. 


496  VITAL  STATISTICS 

every  case  used  in  the  calculation  must  be  accurately 
diagnosed  and  must  be  undoubtedly  one  of  that  disease. 
If  there  is  any  doubt  as  to  preciseness,  it  is  necessary  to 
omit  that  unit. 

2.  The  units  are  to  be  arranged  into  groups.  These 
groups  must  have  dividing  characteristics  so  definite 
that  there  can  be  no  doubt  into  which  group  each  unit 
will  come.  No  unit  must  be  in  more  than  one  group 
at  one  time.  It  is  difficult  to  group  complex  facts  so 
as  to  analyze  them  properly  and  to  discover  all  possible 
phases. 

3.  Having  decided  and  arranged  the  groups,  we  must 
have  a  constant  numerical  standard  by  which  the  relation 
of  the  various  groups  to  the  total  units  may  be  expressed. 
It  is  generally  100  or  some  multiple  of  100. 

4.  We  must  determine  the  variation  in  the  proportion 
or  relation  of  the  component  groups  to  the  whole  in  similar 
series  of  cases.  While  only  an  approximation  to  an  inva- 
riable proportion  may  be  had  in  any  one  series,  it  may  be 
shown  mathematically  that  as  the  number  of  units  in  the 
series  increases  there  is  lessened  variation  and  a  greater 
probability  that  the  proportions  will  approach  uniformity, 
and  that  we  may  calculate  the  limits  of  variation  by 
Poisson's  formula,  as  follows:  If  m  be  the  number  of 
units  in  one  group  in  the  formula  m-\-n  =  q,  and  n  the 
number  in  the  other,  the  proportion  of  m  to  g'  will  be 

— '  g.nd  of  n  to  q,  -,  and  these  proportions  will  vary  in 

/2  77)  7? 

succeeding  series  within  the  limits  indicated  by  2  ^/ — ^ . 
Consequently,  the  greater  the  value  of  q,  the  less  com- 

paratively  will   be  that  of  2  ^ ,  or  the   limit  of 

\     q^ 

variation  trom  -  and  -• 

Example:  Suppose  that  in  a  series  of  1000  cases  of 
diphtheria  700  recover;  then,   according  to  the   above 


NUMERICAL  UNITS  497 

formula,  the  limit  of  possible  variation  in  another  series 
of  1000  similar  cases  would  be  40,  and  the  recoveries 
would  be  between  680  and  720;  whereas,  in  a  like  series 
of  only  100  cases  the  limit  of  variation  would  be  13  and  the 
probable  recoveries  would  vary  between  63  and  77. 

The  arithmetical  mean  is  usually  employed  in  medical 
inquiries,  though  the  increase  in  population  is  often 
estimated  by  geometrical  progression.  The  probable 
error  or  variation  from  the  arithmetical  mean  is  about 
two-thirds  (0.6745)  of  the  mean  error,  which  latter  is  the 
mean  of  the  mean  error  in  excess  and  the  mean  error  in 
deficiency.  The  mean  error  in  excess  is  the  difference 
between  the  mean  of  the  series  and  the  mean  of  all  the 
units  of  the  series  above  the  mean.  The  mean  error 
in  deficiency  is  the  difference  between  the  mean  of  the 
series  and  the  mean  of  all  the  units  below  the  mean. 

The  relative  value  of  two  series  is  as  the  reciprocals  of 
the  squares  of  their  probable  errors.  Thus  if  the  probable 
error  of  series  A  is  10  per  cent,  and  that  of  B  is  2  per 
cent.,  the  value  of  A  to  B  will  be  as  liiy  to  f ,  or  B  will 
be  twenty-five  times  as  valuable  as  A. 

The  relative  value  of  two  or  more  series  is  also  as  the 
square  roots  of  the  numbers  of  units  in  the  respective 
series.  From  the  above  it  is  evident  that  the  results 
from  an  average  cannot  be  absolutely  applied  to  any  par- 
ticular case,  for  there  is  always  the  chance  of  such  varia- 
tion as  may  be  determined  by  Poisson's  formula  or  by  the 
estimation  of  the  probable  error.  We  apply  averages  to 
the  aggregates  of  facts,  and  they  will  approach  exactitude 
if  they  are  founded  on  a  sufficient  number  of  facts.  We 
must  be  careful  in  estimating  the  value  of  means  and 
averages  and  in  giving  credit  or  blame  accordingly.  Guy 
says:  "Averages  are  numerical  expressions  of  probabili- 
ties; extreme  values  are  expressions  of  possibilities." 

Statistical  results  are  frequently  expressed  by  graphic 
representations  (see  Figs.  150  and  151),  and  these  are  very 
valuable,  especially  for  class  or  visual  demonstration. 

The  numerical  units  employed  in  the  study  and  the  cal- 
32 


498 


VITAL  STATISTICS 


culations  of  vital  statistics  are  persons  living  and  persons 
dead,  and  the  groups  into  which  these  units  are  classified 
are  characterized  by  such  distinctions  as  age,  sex,  race, 
occupation,  locality,  etc.  The  sources  from  which  we 
derive  our  information  regarding  these  units  are  two,  viz., 
the  census  or  count,  which  every  civilized  country  makes 
periodically,  and  the  returns  of  births,  marriages,  deaths, 
and  cases  of  contagious  disease  made  to  local  governing 
sanitary  bodies,  such  as  boards  of  health,  etc.     These 


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Fig.  150. — Graphic  chart,  showing  percentages  of  typhoid  fever  deaths 
in  total  mortality  in  four  cities.  Unbroken  line,  Chicago ;  lower  line,  New 
York;  short  dashes,  Philadelphia;  long  dashes,  Boston. 

latter  returns  localize  the  units  and  help  especially  in  the 
classifications  in  which  locality  is  a  factor. 

The  census  returns  give  not  only  the  population,  but 
also  particulars  as  to  sex,  age,  race,  occupation,  etc.  Of 
these  the  age-record  is  most  important,  as  the  death-rate 
varies  most  according  to  age. 

The  natural  increment  of  a  population  is  the  excess  of 
births  over  deaths,  but  the  actual  increment  differs  from 
this,  however,  according  to  the  difference  between  emigra- 
tion and  immigration.    And  as  the  rate  of  increase  does 


ESTIMATION  OF  POPULATION 


499 


not  always  remain  the  same,  estimates  of  population  at 
times  other  than  of  the  census  cannot  be  exactly  accurate. 
Thus,  we  may  have  a  lowered  death-rate  and  yet  a 
decrease  in  both  the  natural  and  actual  increment,  owing 
to  a  greatly  lowered  birth-rate  and  to  increased  emigra- 
tion, both  of  which  may  be  primarily  due  to  a  long  period 
of  oppression  or  financial  distress.    However,  to  estimate 

FROM   UNITED  STATES  MORTALITY  STATISTICS  1913 

1900  1901  1902  1903  1904  1905 1906  1907  1908  1909  1910  19111912  1913 

210 

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Fig.  151.— Chart  from  U.  S.  Mortality  Statistics,  1913. 


the  population  for  times  other  than  the  census  year,  we 
assume  that  the  rate  of  increase,  whether  positive  or 
negative,  that  prevailed  between  the  last  two  census 
enumerations  will  continue  until  the  next  is  taken. 

Now,  as  populations  increase  in  regular  geometrical 
progression  when  the  rate  of  increase  is  constant,  which 
we  assume,  the  growth  is  after  the  manner  of  compound 


500  VITAL  STATISTICS 

interest.  Thus,  if  a  population  of  10,000  increases  by 
2  per  cent,  annually,  at  the  end  of  the  first  year  it  will 
number  10,200,  at  the  end  of  the  second  year  10,404, 
etc.    Hence,  it  can  readily  be  shown  that 

logarithm  R  =  —  (log.  P'  —  log.  P),  where  R  is  the 

annual  ratio  of  increase,  P  the  population  of  the  census 
before  the  last,  and  P'  the  population  of  the  last  census. 
If  we  now  multiply  the  logarithm  of  R,  the  annual  ratio 
of  increase,  by  the  number  of  years  since  the  last  census, 
and  add  to  it  the  logarithm  of  the  last  census  (log.  P') 
we  will  have  the  logarithm  of  the  population  at  the 
middle  of  the  given  year — e.  g., 

Q  (log,  of  the  pop.  1890  -  log,  pop.  1880)  ^  ,  ^  ^^^ 

8 — 1-  log.  pop.  1890  = 

logarithm  of  the  population  on  June  30,  1898. 

For  the  reasons  already  given,  such  an  estimate  will 
not  be  absolutely  accurate,  and  it  would,  consequently, 
be  well  to  have  a  census  taken  every  five  years  for  certain 
data.  The  more  accurate  the  estimate  for  any  year  hap- 
pens to  be,  the  more  reliable  will  be  the  statistical  results. 
It  is  also  to  be  noted  that  in  this  country  the  census  is 
taken  at  the  middle  of  the  year,  and  that  death-rates,  etc., 
are  based  on  the  population  estimated,  as  above,  for  the 
middle  of  the  given  year. 

Another  method  of  approximately  estimating  the  popu- 
lation in  small  and  slowly  increasing  districts  is  to  assume 
the  growth  to  be  by  arithmetical  progression,  and,  there- 
fore, to  add  to  the  population  of  the  last  census  one-tenth 
of  the  difference  between  it  and  the  population  of  the 
preceding  census  for  every  year  since  the  last  census. 
We  may  also  estimate  the  population  from  the  number 
of  houses  and  use  this  as  a  check  on  either  of  the  above 
estimates.  The  number  of  persons  living  in  each  house 
averages  about  the  same  for  each  city,  but  differs  for 
different  cities.  So  also  the  ratio  of  the  school  registra- 
tion to  the  total  population,  which  is  apt  to  remain  rela- 


UNIFORM  REGISTRATION  METHODS  501 

lively  constant  for  any  stable  community,  may  be  used 
to  detennine  the  population  for  a  given  year.  Local 
authorities  always  tend  to  overestimate  the  population, 
and  a  police  census  is  invariably  too  high. 

As  has  been  stated,  we  get  the  number  of  births,  mar- 
riages, deaths,  etc.,  from  the  registration  records,  the 
proper  data  being  furnished  to  the  registration  bureau  by 
duly  authorized  persons.  For  instance,  the  law  should 
require  a  burial  permit  for  each  death  in  order  to  identify 
the  person  and  to  guard  against  criminal  acts  or  neglect, 
and  the  death  certificate  on  which  the  burial  permit  is 
issued  should  give  the  name,  sex,  color,  age,  occupation, 
and  especially  the  cause  of  death  of  the  deceased.  The 
diagnosis  concerning  this  last  item  should  be  as  correct  as 
possible,  and  the  primary  as  well  as  the  secondary  cause 
of  death  should  be  given.  And  while  it  is  difficult  to 
determine  the  actual  cause  of  death  in  many  cases  without, 
and  sometimes  even  by  a  postmortem  examination,  there 
is  fortunately  not  much  uncertainty  usually  in  diagnosing 
the  diseases  of  which  we  most  want  statistical  informa- 
tion, especially  the  so-called  preventable  or  infectious 
diseases. 

As  a  consequence  of  the  above,  the  certificate  as  to  the 
cause  of  death  will  need  to  be  signed  by  some  one  compe- 
tent to  determine  that  cause,  viz.,  by  an  educated  physi- 
cian; and  it  is  therefore  necessary  that  the  State  should 
define  who  is  and  who  is  not  an  "educated  physician.*' 
And  as  this  information  and  the  other  required  returns 
which  the  physician  makes,  as  well  as  his  professional 
services  in  general,  are  for  the  sake  and  benefit  of  the 
citizens  of  the  State,  it  is  evidently  to  the  State's  interest 
that  it  be  very  careful  and  explicit  as  to  the  qualifications 
of  the  physicians  whom  it  allows  to  practise  within  its 
borders. 

Another  reason  for  the  enforced  return  of  a  certificate 
and  the  issuance  of  a  burial  permit  for  every  death  is  that 
this  is  about  the  only  way  in  which  it  is  possible  to  secure 
a  record  of  all  the  deaths.    Any  system  for  collating  the 


502  VITAL  STATISTICS 

list  of  deaths  only  at  the  end  of  the  year  will  fail  to  record 
from  25  to  40  per  cent,  of  the  number. 

The  statements  made  in  the  introductory  chapter 
and  elsewhere  show  the  importance  of  vital  statistics 
in  determining  the  sanitary  conditions  and  improvement 
of  communities.  In  order  that  comparisons  and  correct 
judgments  may  be  readily  made,  it  is  evident  that  all 
classifications,  returns,  and  registrations  should  be  on  a 
basis  or  system  as  uniform  as  possible,  but  almost  the 
opposite  has  obtained,  since  almost  every  State,  city,  or 
local  authority  has  used  its  own  system  and  without  any 
concert  of  action  until  comparatively  recently.  Accord- 
ingly, in  order  to  amend  this  and  to  secure  not  only 
uniform,  but  also  correct  and  thorough  returns  from  the 
whole  country,  the  Division  of  Vital  Statistics  of  the  U.  S. 
Census  Office  is  making  extraordinary  efforts  to  bring 
about  uniform  legislative  requirements  in  the  various 
States  and  to  secure  the  adoption  of  the  International 
Classification  of  Causes  of  Death,  which  is  intended  "to 
harmonize  the  features  of  the  most  generally  used  systems 
in  order  to  afford  a  common  basis  of  union,"  and  which 
has  been  adopted  by  the  U.  S.  Census  Office  for  the  com- 
pilation of  mortality  statistics.  To  this  end  a  circular  has 
been  sent  to  the  physicians  of  the  country  "  describing  the 
details  required  by  the  Standard  Certificate  of  Death  (see 
next  page),  and  giving  the  titles  of  the  International 
Classification  of  Causes  of  Death,  with  explanatory  notes 
showing  the  significance  of  various  terms  to  the  titles 
under  which  they  are  compiled,  and  a  list  of  indefinite  and 
unsatisfactory  terms  very  frequently  used  in  reporting 
deaths,  with  a  statement  of  why  such  statements  are 
unsatisfactory."  This  circular  is  very  instructive,  and  its 
recommendations  should  henceforth  be  observed  by  all 
physicians  in  making  death  returns.^ 

1  This  circular  can  doubtless  be  had  on  application  to  the  Division 
of  Vital  Statistics  of  the  Census  Office  at  Washington,  together  with  a  cir- 
cular on  Medical  Education  in  Vital  Statistics,  relating  to  the  instruc- 
tion of  medical  students  in  registration  methods,  uses  of  registration 
data,  and  the  duties  and  obligations  of  physicians ;  and  one  on  Practical 
Registration  Methods,  for  the  information  of  local  registrars, 


PACTORS  AFFECTING  MORTALITY-RATE^       503 


8-209.  MARGIN    RESERVED    FOR    BINDING. 

y.  S.  No.  98.         Write  Plainly,  with  Unfading  Ink— this  is  a  Permanent  Record. 

N.B.— Every  item  of  information  should  be  carefully  supplied.  AGE  should  be 
stated  EXACTLY.  PHYSICIANS  should  state  CAUSE  OF  DEATH  in  plain 
terms,  that  it  may  be  properly  classified.  The  "Special  Information  for 
persons  dying  away  from  home  should  be  given  in  every  instance. 


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504  VITAL  STATISTICS 

The  gross  death-rate  varies  with  the  size  of  the  com- 
munity. Newly  settled  communities  have  a  lower  death- 
rate  than  older  ones,  because  the  proportion  of  adults  is 
larger  and  of  children  smaller  in  the  former.  With  large 
communities  and  short  periods  the  probabilities  of  error 
are  very  great,  and  the  longer  the  period  the  less  likelihood 
of  error.  Birth-rates,  marriage-rates,  and  death-rates  are 
usually  calculated  as  rates  per  thousand  of  the  popula- 
tion living  at  the  middle  of  the  given  year,  and  are 
determined  by  multiplying  the  number  of  births,  mar- 
riages, or  deaths  by  1000,  and  dividing  the  product  by 
the  population. 

What  were  looked  upon  as  fair  maximum  death-rates 
a  decade  or  more  ago  are  now  considered  to  be  too  high, 
and  the  average  rate  of  the  present  closely  approximates 
the  minimum  of  the  comparatively  recent  past.  However, 
if  the  death-rates  of  any  community  are  continuously 
reported  as  much  below  the  average  for  similar  popula- 
tions, the  chances  are  that  the  population  has  been  over- 
estimated or  that  all  deaths  have  not  been  recorded.  If 
higher  than  this  average,  there  is  probably  some  special 
cause  for  the  high  mortality. 

In  statistical  computations  we  must  exclude  the  popu- 
lations and  deaths  in  hospitals,  prisons,  etc.,  except  for 
such  of  the  inmates  as  belong  to  the  district  in  which 
such  institution  is  located. 

To  find  the  weekly  or  daily  death-rate,  the  number  of 

deaths  for  the  week  or  day  must  be  multiplied  by  1000 

and  divided  by  the  so-called  weekly  or  daily  population: 

,1  11  1  ^.         total  population   ^.     ,  ., 

the  weekly  population  = J^  tl  ^ ;  the  daily  popu- 

,     .          total  population    _^-  , .  .    .  , 

lation 94.00A ^^^  monthly  population  equals 

the  daily  population  multiplied  by  the  number  of  days  in 
the  particular  month. 

The  zymotic  death-rate  is  the  rate  from  the  seven 
principal  zymotic  or  infectious  diseases,  viz.,  smallpox, 
measles,    scarlatina,    diphtheria,    whooping-cough,    fever 


DEFINITION  OF  TECHNICAL  TERMS  505 

(typhoid,  typhus,  or  other  continued  fever),  and  diarrhea.^ 
It  is  given  per  1000  of  population,  and  in  the  same  way 
we  can  give  the  special  rate  for  any  particular  disease,  but 
this  is  now  usually  stated  as  the  rate  per  100,000  of  popu- 
lation. ¥oT  example,  the  average  annual  zymotic  death- 
rate  for  England  and  Wales  for  the  decade  from  1861  to 
1870  was  4.11,  for  1871-80  it  was  3.36,  and  for  1881-90, 
2.35 — a  striking  proof  of  the  decided  benefits  follo^^^ng 
proper  attention  to  hygiene  and  sanitation. 

The  mortality  from  certain  diseases  is  affected  by  age, 
sex,  race,  occupation,  density  of  population,  seasons, 
cyclical  changes,  etc. 

Contrary  to  the  general  rule,  the  rate  of  infant  mortality 
is  not  expressed  per  thousand  of  population,  but  measured 
by  the  proportion  of  deaths  of  infants  under  one  year  to 
the  births  registered  in  that  year,  and  is  determined  by 
multiplying  the  number  of  deaths  by  1000  and  dividing 
the  product  by  the  number  of  births. 

The  infant  mortality-rate  is  always  high,  owing  to 
various  causes,  viz.,  early  marriages  and  weakly  parents, 
hereditary  tendencies  or  diatheses,  insanitary  surround- 
ings and  unfavorable  social  conditions,  improper  feeding, 
insuflBcient  clothing,  infant  life  insurance,  etc. 

Death-rates  vary  greatly  for  the  different  ages,  being 
much  higher  for  the  first  five  years  of  life.  For  this 
reason  it  is  well  to  express  the  death-rate  of  children 
under  five  as  the  rate  per  thousand  of  children  under  that 
age,  rather  than  as  a  proportion  of  the  total  number  of 
deaths.  Otherwise,  a  town  with  a  large  number  of  chil- 
dren might  apparently  have  an  abnormally  high  death- 
rate.  There  might  also  be  a  difl^erence  in  the  death-rates 
of  two  localities  due  to  sex-distribution,  for  the  sexes 
differ  in  their  susceptibility  and  resistance  to  the  various 
diseases.  More  boys  are  born  everywhere  than  girls,  but 
more  males  die  than  females,  so  that  the  tendency  is  to  a 
preponderance  of  the  latter,  except  in  newly  settled  coun- 

»  Wilson,  Hand-book  of  Hygiene,  8th  ed.,  p.  570. 


506  VITAL  STATISTICS 

tries  or  localities.  Age-distribution  and  sex-distribution 
favor  a  low  mortality  in  rapidly  increasing  towns,  new 
localities,  and  manufacturing  districts;  in  rural  districts 
they  tend  to  increase  the  death-rate. 

Consequently,  when  the  death-rates  of  two  or  more 
towns  or  localities  are  to  be  compared,  there  must  be  cor- 
rections for  age-distribution  and  sex-distribution.  The 
mean  annual  death-rate  of  the  country  for  each  age  and  sex 
for  the  decade  preceding  the  last  census  is  applied  to 
the  town  or  district,  with  age-distribution  and  sex-distri- 
bution according  to  the  last  census.  The  total  number  of 
deaths  thus  calculated,  multiplied  by  1000,  and  divided 
by  the  population  of  the  last  census,  gives  the  standard 
death-rate  of  that  town.  The  mean  annual  death-rate  of 
the  country  divided  by  the  standard  death-rate  gives  the 
factor  for  correction,  which  being  multiplied  by  the  re- 
corded death-rate  of  any  year  gives  the  corrected  death- 
rate.  The  comparative  mortality  figure  is  determined  by 
multiplying  the  corrected  local  death-rate  by  1000  and 
dividing  by  the  death-rate  for  the  whole  country,  and 
only  indicates  that  the  same  population  which  gave  1000 
deaths  in  the  whole  country  gave  or  would  have  given  so 
many  deaths  in  the  town  or  district  in  question. 

The  morbidity-rate  or  sick-rate  of  a  community  is  diffi- 
cult to  estimate,  since  there  is  usually  no  complete  record 
and  registration  of  cases  of  disease.  Where  returns  are 
required  to  be  made  of  the  infectious  diseases,  the  mor- 
bidity due  to  them  may  be  determined  in  the  same  way 
as  the  mortality  for  the  locality.  It  is  estimated  that 
there  is  a  total  of  about  two  years'  sickness  in  a  com- 
munity for  every  death,  and  members  of  beneficial 
societies  are  said  to  average  about  one  and  one-half 
weeks'  sickness  annually.  "Applying  this  estimate  to 
the  United  States,  in  which  about  1,500,000  persons 
die  per  annum,  there  are  probably  at  all  times  about 
3,000,000  persons  seriously  ill.  This  means  an  average 
of  thirteen  days  for  each  inhabitant."^ 

^  Report  on  National  Vitality,  Fisher,  p.  34. 


AVERAGE  DURATION  Of  LIFE  507 

In  this  connection,  the  following  definitions  are  given 
of  terms  that  are  employed  in  discussions  of  vital  statis- 
tics, especially  in  relation  to  longevity: 

The  mean  age  at  death  of  a  population  is  the  average 
age  at  which  death  occurs  in  that  population,  and  is  indi- 
cated by  the  total  of  the  ages  at  death  divided  by  the 
number  of  deaths.  Inasmuch  as  it  depends  largely  on  the 
age-distribution  of  the  population,  it  is  neither  a  good  test 
of  longevity  nor  of  sanitary  conditions,  except  when  it  is 
calculated  or  taken  from  life-tables  for  an  entire  gen- 
eration. 

The  probable  duration  of  life  is  the  age  at  which  any 
number  of  children  born  will  be  reduced  one-half,  the 
chances  thus  being  even  that  each  will  survive  to  that  age. 

For  a  million  children  the  probable  duration  of  life  is 
for  males  less  than  forty-five  years;  for  females,  forty- 
seven  years. 

The  mean  duration  of  life  is  the  same  as  the  mean  age 
at  death  when  the  population  is  stationary  as  to  age- 
distribution  and  sex-distribution.  Otherwise,  it  is  indi- 
cated by  the  mean  after-lifetime. 

The  expectation  of  life  is  the  mean  after-lifetime  of  a 
person  at  any  age,  as  indicated  by  a  life-table;  or,  in  other 
words,  it  is  the  average  number  of  years  which  persons 
of  that  age  continue  to  live.  At  birth  it  is  identical  with 
the  mean  duration  of  life,  and  "  as  applied  to  communities, 
it  is  the  mean  lifetime  of  a  generation  of  persons  traced 
by  the  life-table  method  from  birth  to  death,  and  is  the 
only  true  test  of  the  health  of  populations."  According 
to  Farr,  "a  life-table  is  a  barometer  which  indicates  the 
exact  measure  of  the  duration  of  life  under  given  circum- 
stances, and  is  indispensable  in  gauging  the  influence  of 
sanitary  or  insanitary  conditions." 

The  essential  factors  of  a  life-table  are  the  number  and 
ages  of  the  living  and  the  number  and  ages  of  those  that  die, 
and  these  factors  are  obtained  from  the  mean  population 
for  each  age  and  sex  and  from  the  total  death-returns 
between  two  censuses. 


508  VITAL  STATISTICS 

"Contrary  to  common  impression,  there  is  no  iron  law 
of  mortality.  Recent  statistics  for  India  show  that  the 
average  duration  of  life  there  is  less  than  twenty-five 
years.  In  Sweden  it  is  over  fifty  years;  in  Massachusetts, 
forty-five  years.  The  length  of  life  is  increasing  wherever 
sanitary  science  and  preventive  medicine  are  applied. 
In  India  it  is  stationary.  In  Europe  it  has  doubled  in 
three  and  a  half  centuries.  The  rate  of  increase  during 
the  seventeenth  and  eighteenth  centuries  was  about  four 
years  per  century;  during  the  first  half  of  the  nineteenth 
century,  about  nine  years  per  century;  during  the  latter 
half  of  the  nineteenth  century,  about  seventeen  years  per 
century.  And  in  Germany,  where  medical  and  sanitary 
science  has  reached  the  highest  development,  about 
twenty-seven  years  per  century.  The  only  comparative 
statistics  available  in  this  country  are  for  Massachusetts, 
where  life  is  lengthening  at  the  rate  of  about  fourteen 
years  per  century,  or  half  the  rate  in  Germany."^ 

^  Abstract  of  Report  on  National  Vitality,  Fisher. 


CHAPTER  XVI. 
THE  EXAMINATION  OF  AIR,  WATER,  AND  FOOD. 

In  this  final  chapter  the  author  has  endeavored  to 
arrange  a  series  of  methods  for  the  examination  or  analysis 
of  the  subjects  respectively  considered  in  such  a  manner 
that  anyone  who  has  had  a  little  laboratory  experience 
may  be  enabled  to  determine  their  hygienic  conditions, 
sanitary  influence  or  degree  of  purity,  and  this  at  the  cost 
of  a  minimum  of  time  and  expense. 

The  methods  outlined  have  been  selected  from  a  variety 
of  sources,  and  some  have  been  especially  modified  for  the 
purpose;  so  that  while  it  is  not  claimed  that  they  will  give 
the  absolutely  accurate  results  desired  by  the  professional 
bacteriologist  or  chemist,  nor  that  they  will  suffice  as  a 
basis  for  expert  testimony  in  court  or  to  establish  legal 
rights,  it  is  believed  that,  if  carefully  carried  out,  they 
will  not  fail  to  yield  the  information  sought  for,  viz., 
whether  the  sample  of  air,  water,  or  food  examined  is 
sanitarily  pure  or  safe  for  use  within  the  accepted  limits. 

Only  such  apparatus  is  to  be  used  as  can  be  readily 
obtained  or  improvised  without  much  expense,  and  every 
effort  has  been  made  to  render  everything  clear  to  the 
student  and  reader,  so  that  he  may  not  hesitate  to  un- 
dertake the  necessary  investigation  whenever  occasion 
requires  or  an  opportunity  offers. 

For  further  details  regarding  any  of  the  methods,  should 
these  be  found  necessary,  reference  may  be  made  to  the 
text-books  indicated,  as  they  will  render  clear  any  points 
that  may  here  seem  uncertain  or  abstruse. 

AIR. 

The  solid  impurities  in  the  atmosphere  may  be  col- 
lected for  microscopic  examination  as  follows:    Tightly 

(509; 


510     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

cork  a  large  glass  funnel  and  fill  it  with  cracked  ice.  As 
the  aqueous  vapor  of  the  air  condenses  on  the  exterior, 
the  dust  particles  adhere  to  the  moistened  glass,  and  are 
carried  down  by  the  condensed  water  into  a  vessel  placed 
below,  in  which  they  are  allowed  to  settle.  From  this 
they  are  transferred  by  means  of  a  pipette  to  clean  slides 
and  examined  under  the  microscope.  Other  methods 
that  may  be  used  to  collect  the  dust  are  oiled  plates; 
paper,  cloth  or  cotton  wool  filters;  wash  bottles,  etc. 

To  make  a  qualitative  bacteriological  examination  the 
air  may  also  be  drawn  through  sterilized  glass  tubes  coated 
interiorly  with  gelatin.  Bacteria  and  their  spores,  moulds, 
etc.,  adhere  to  this  coating,  and  from  each  individual  or 
group  of  individuals  colonies  develop,  from  which  pure 
cultures  and  subsequent  bacteriological  experiments  may 
be  made;  or  the  sterilized  gelatin  may  be  exposed  in  flat 
(Petri)  dishes  to  the  air  for  a  short  time  to  allow  the  bac- 
teria, etc.,  to  fall  on  the  surface.  The  tubes  or  dishes  are 
then  covered  and  set  aside  to  allow  the  colonies  to  develop. 

To  make  a  quantitative  bacteriological  examination  a 
known  quantity  of  air  may  be  drawn  through  a  small 
tube  filled  with  sterilized  pulverized  sugar.  The  sugar 
is  then  transferred  to  tubes  or  flasks  of  melted  and 
sterilized  gelatin,  and  dissolving  leaves  the  bacteria,  etc., 
free  to  develop  in  the  gelatin,  which  may  be  poured  upon 
sterilized  Petri  dishes  before  cooling.  A  temperature 
just  sufficient  to  melt  the  gelatin  will  not  be  too  warm 
to  harm  the  bacteria.  The  number  of  colonies  that 
develop  may  be  assumed  to  represent  the  number  of 
living  microorganisms  in  the  volume  of  air  drawn  through 
the  tube. 

The  relative  humidity  or  percentage  of  moisture  in 
the  air  is  determined  by  some  form  of  hygrometer,  of 
which  one  of  the  most  convenient  is  the  psychrometer, 
which  is  simply  a  combination  of  a  dry-  and  a  wet-bulb 
thermometer.  The  latter  has  its  bulb  enclosed  in  a  jacket 
of  absorbent  wicking^  muslin,  or  silk,  which  dips  into  a 


EXAMINATION  OF  AIR 


511 


Fig.  152. — Sling  psychrometer. 


512     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

small  reservoir  of  clean,  soft  water.  The  thermometer 
bulb  is  thus  kept  wet  by  capillary  attraction,  and,  unless 
the  air  be  "saturated"  with  aqueous  vapor,  evaporation 
takes  place  more  or  less  rapidly,  heat  is  abstracted  or 
made   "latent,"   and  the  temperature,   as  indicated  by 


Fig.   153. — The  Tyeos  hygrodeik. 

this  thermometer,  is  lowered.  Hence,  by  the  difference 
in  reading  of  the  two  thermometers  we  may  determine 
not  only  the  relative  humidity  of  the  atmosphere,  but 
also  the  "dew  point,"  weight  of  vapor  per  cubic  foot  of 
air,  and  even  the  "tension"  or  influence  upon  barometric 
pressure  due  to  the  presence  of  this  vapor.    These  results 


PSYCHROMETER  AND  HYGRODEIK  513 

are  usually  and  most  conveniently  determined  by  using 
tables  that  have  been  prepared  for  all  variations  of  tem- 
perature and  humidity  within  practical  limits,  and  which 
are  supplied  with  the  instruments.  The  "  hygrodeik/* 
however,  has  a  chart  fixed  between  the  two  thermome- 
ters which  shows  graphically  by  a  series  of  curved  lines 
and  a  movable  indicator  all  the  facts  that  would  be 
derived  by  using  the  official  tables.  A  sling  psychrometer 
is  one  devised  so  that  it  may  be  whirled  rapidly  in  the 
air,  thus  facilitating  evaporation  from  the  wet-bulb  and 
lowering  to  a  constant  temperature. 

Test  for  Carbon  Dioxide,  CO2. — Boom's  Modification 
of  Wolpert's  MetJiod. — Make  a  mark  on  any  test-tube, 
say  one  inch  from  the  bottom.  Fix  the  bulb  of  an  atomizer 
to  a  glass  capillary-tube  sufficiently  long  to  reach  to  the 
bottom  of  the  test-tube,  and  in  such  a  manner  that  a 
definite  quantity  of  air  is  forced  from  the  bulb  through 
the  tube  at  each  compression.  To  use:  Fill  the  test- 
tube  exactly  to  the  mark  with  a  saturated  solution  of 
lime-water,  take  the  apparatus  into  the  out-door  air 
and  driving  the  air  slowly  through  the  lime-water  each 
time,  find  out  how  many  compressions  of  the  bulb  are 
needed,  to  make  the  lime-water  just  turbid  enough  to 
obscure  a  pencil-mark  on  white  paper  placed  beneath 
the  test-tube  and  viewed  from  above.  Then  rinse  out  the 
test-tube,  fill  exactly  to  the  mark  again  with  lime-water, 
and  repeat  the  process  in  the  room  the  air  of  which  is  to 
be  examined.  We  then  assume  that  the  out-door  air  con- 
tains the  normal  amount  of  carbon  dioxide — 0.04  per  cent, 
(unless  we  happen  to  know  the  actual  amount  in  the 
atmosphere  at  the  time),  and  estimate  the  percentage  of 
carbon  dioxide  in  the  air  of  the  room  by  the  following 
proportion:  Let  .T  =  the  percentage  of  CO2  in  the  air  of 
the  room.  Then  the  number  of  compressions  of  the  bulb 
required  in  the  outer  air  is  to  the  number  of  compressions 
required  in  the  room  as  x  is  to  0.04.  If  the  actual  per- 
centage of  CO2  in  the  outer  air  is  known,  substitute  this 
for  the  0.04  per  cent,  in  the  formula.  Care  must  be 
33 


514     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

taken  in  using  this  device  not  to  draw  any  of  the  lime- 
water  into  the  bulb. 

A  Modification  of  Angus  Smith's  Method. — To  a  mod- 
erately large,  wide-mouth  bottle  (one-quart)  fit  a  per- 
forated rubber  stopper,  the  perforation  being  just  large 
enough  to  admit  the  tip  of  a  1  c.c.  pipette;  first  fill  the 
bottle  with  the  air  of  the  room  by  filling  it  with  water 
and  then  emptying  it  in  the  room,  taking  care  that  the 
entering  air  does  not  bubble  through  the  out-going  water. 
Fit  ia  the  stopper  and  introduce  1  c.c.  at  a  time  of  a 
standardized  alkaline  solution,  slightly  colored  with  a 
few  drops  of  a  neutral  alcoholic  solution  of  phenolphtha- 
lein;  close  the  perforation  with  a  piece  of  glass  rod  and 
shake  the  bottle  well  after  each  addition  of  the  alkali, 
continuing  until  the  color  ceases  to  be  discharged  by  the 
carbonic  acid  of  the  contained  air.  Then,  since  the 
quantity  used  of  the  alkali  solution  indicates  a  certain 
definite  amount  of  carbon  dioxide. 

The  number  of  c.c.  of  solution  v^ed  multiplied  by  the 
amount  of  CO2  each  c.c.  represents,  multiplied  by  100, 
and  divided  by  the  capacity  of  the  bottle  in  c.c.  less  the 
number  of  c.c.  of  solution  u^ed  —  x  =  the  percentage  of 
CO2  in  the  air  examined. 

A  suitable  alkaline  solution  may  be  prepared  as  fol- 
lows: Dissolve  exactly  2.409  grammes  of  pure  sodium 
carbonate  (free  from  the  water  of  crystallization)  in  1 
liter  of  distilled  water.  Only  a  fraction,  say  one-fourth 
or  one-tenth,  of  this  quantity  need  be  made  up  at  a  time. 
Each  c.c.  of  this  solution  will  neutralize  to  1  c.c.  of  CO2. 
For  use:  To  10  c.c.  of  this  solution  add  a  few  drops  of 
neutral  alcoholic  solution  of  phenolphthalein  and  dilute 
to  100  c.c.  Each  c.c.  of  this  dilute  solution  is  then  equiva- 
lent to  0.1  c.c.  of  CO2,  and  used  as  above  will  give  close 
results.  The  phenolphthalein  is  used  as  an  indicator,  as 
the  pink  or  rose  color  due  to  it  disappears  when  sufficient 
carbon  dioxide  is  absorbed  to  exactly  neutralize  the 
alkalinity  of  the  soda  solution.  The  stock  solution  should 
be  kept  in  well-filled,  tightly  stoppered  bottles. 


TEST  FOR  CARBON  DIOXIDE  IN  AIR 


515 


Example:    If  9  c.c.  of  the  above  dilute  solution  be  used, 
and  the  capacity  of  the  bottle  is  1200  c.c,  then 
9X0.1X10Q_  90    _     _..,.-.. 
1200-9      -1191 -"^-^-^^^^^ 
the  percentage  of  CO2  in  the  air  of  the  room. 

Pettenkofers  Method.  —  This  test, 
like  the  preceding  one,  depends  upon 
the  fact  that  the  acid  carbon  dioxide 
in  a  measured  sample  of  air  tends  to 
neutralize  the  alkalinity  of  a  stock 
solution  of  calcium  or  barium  hydrate 
when  the  latter  is  agitated  with  the 
given  volume  of  air,  and  that  the 
amount  of  carbon  dioxide  can  thus 
be  measured  by  the  loss  of  alkalinity 
in  the  solution.  The  absorption  of 
the  carbon  dioxide  is  more  rapid  if  a 
solution  of  barium  hydrate  instead 
of  lime-water  (calcium  hydrate)  is 
used,  the  former  taking  up  the  gas 
within  an  hour  or  so,  whereas  eight 
or  ten  hours  are  needed  for  its  com- 
plete absorption  by  the  lime-water. 
However,  the  latter,  which  is  a 
well-known  solution  of  the  official 
pharmacopoeia,  is  more  readily  ob- 
tained and  gives  equally  good  re- 
sults, if  proper  time  be  given  to  the  test.  The  barium 
hydrate  solution  is  made  by  dissolving  about  4.5  grammes 
of  barium  hydrate  and  0.5  gramme  of  barium  chloride 
in  a  liter  of  distilled  water,  which  has  been  previously 
boiled  to  drive  off  any  contained  carbon  dioxide.  The 
solution,  if  made  up  in  considerable  quantity  for  repeated 
tests,  is  best  kept  in  a  bottle  with  a  stopper  having  a 
U-tube  for  an  inlet,  as  in  Fig.  154.  This  U-tube  contains 
small  pieces  of  pumice  soaked  while  hot  in  strong  caustic 
potash  solution,  and  prevents  the  ingress  of  CO2  from 
the  air  when  the  liquid  is  drawn  from  the  bottle.     In 


Fig.  154.— Bottle  for 
barium  hydrate.  (Har- 
rington.) 


516     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

the  description  of  the  test  the  term  lime-water  will  be 
used  to  indicate  the  alkaline  solution,  although  it  be 
prepared  with  either  base. 

The  Test. — The  air  to  be  tested  is  collected  in  one  or 
more  large,  clean  bottles,  the  exact  capacity  of  each 
having  previously  been  ascertained  and  noted.  The 
bottles  may  be  filled  by  pumping  in  the  air  with  a  bellows 
or  by  first  filling  with  water  and  then  removing  the  latter 
by  siphoning  or  by  carefully  decanting  it,  care  being 
taken  that  the  air  does  not  bubble  through  the  water 
which  readily  absorbs  carbon  dioxide. 

Into  each  bottle  containing  an  air  sample  an  exact 
quantity  of  the  lime-water,  say  50  c.c,  is  introduced, 
the  bottle  quickly  stoppered,  and  then  well  shaken,  so 
that  the  air  may  be  thoroughly  washed  with  the  solution. 
The  shaking  is  to  be  repeated  at  intervals  until  the 
necessary  time  for  complete  absorption  of  the  gas  has 
elapsed.  If  the  lime-water  is  measured  into  the  bottles 
by  means  of  a  pipette,  care  must  be  had  that  the  delivery 
is  not  hastened  by  blowing  through  the  pipette,  since 
the  carbon  dioxide  of  the  expired  air  would  thus  vitiate 
the  test.  The  strength  of  the  lime-water,  being  as  yet 
unknown,  is  now  determined  by  means  of  a  solution  of 
oxalic  acid  of  such  a  strength  that  1  c.c.  corresponds  in 
alkalinity  to  0.5  c.c.  of  CO2.  (Such  a  solution  is  made  by 
dissolving  exactly  2.808  grammes  of  pure  crystallized 
oxalic  acid  in  1  litre  of  distilled  water.) 

Supposing  that  50  c.c.  of  lime-water  was  introduced 
into  each  bottle  containing  air  to  be  tested,  exactly  25  c.c. 
of  the  stock  lime-water  is  measured  into  a  clean  beaker, 
into  which  the  oxalic  acid  solution  is  run  from  a  graduated 
burette  until  the  alkalinity  of  the  lime-water  is  just 
destroyed,  the  neutral  point  being  indicated  by  means  of 
a  phenolphthalein  solution,  which  may  have  been  pre- 
viously added  to  the  stock  solution,  or  a  few  drops  may 
be  placed  with  it  in  the  beaker.  The  phenolphthalein 
retains  its  color  as  long  as  the  solution  is  alkaline,  but 
loses  it  the  moment  the  neutral  point  is  reached.    When 


PETTENKOFEWS  TEST  FOR  CARBON  DIOXIDE    517 

the  lime-water  is  exactly  neutralized,  the  exact  amount 
of  the  acid  solution  used  is  noted.  Then,  after  the  time 
necessary  to  allow  the  complete  absorption  of  the  carbon 
dioxide  in  each  testing  bottle  by  the  lime-water  therein, 
25  c.c.  of  that  lime-water  is  measured  into  a  beaker, 
and  the  alkalinity  exactly  determined  by  means  of  the 
oxalic  acid  solution  in  the  same  manner  as  was  done  with 
the  stock  solution. 

Now,  inasmuch  as  part  of  the  alkalinity  of  the  lime- 
water  which  was  in  the  bottle  has  already  been  neutralized 
by  the  carbon  dioxide  in  the  air  of  the  bottle,  it  will 
require  less  of  the  acid  solution  to  neutralize  the  lime- 
water  from  the  bottle  than  was  required  for  the  same 
quantity  of  stock  lime-water,  and  as  1  c.c.  of  the  acid 
solution  corresponds  to  0.5  c.c.  of  carbon  dioxide,  the 
difference  in  the  amounts  of  acid  solution  used  expressed 
in  c.c.  will  express  the  number  of  c.c.  of  carbon  dioxide 
in  the  volume  of  air  in  the  bottle.  For,  though  each  c.c. 
of  acid  solution  is  equivalent  to  only  0.5  c.c.  of  carbon 
dioxide,  the  loss  of  alkalinity  of  only  one-half  the  lime- 
water  primarily  introduced  into  the  bottle  has  been 
determined,  and  the  total  loss  of  alkalinity  would  have 
to  be  expressed  by  multiplying  0.5  c.c.  CO2  by  twice 
the  difference  in  c.c.  between  the  amount  of  acid  used  in 
testing  25  c.c.  of  the  stock  lime-water  and  that  used  in 
testing  the  25  c.c.  (one-half)  of  the  lime-water  from  the 
bottle.  But  twice  0.5  =  1.  Therefore  the  difference 
between  the  readings  in  the  two  tests  gives  the  amount 
of  carbon  dioxide  in  the  air  in  the  bottle.  The  quantity 
-of  carbon  dioxide  in  the  bottle  having  been  thus  determined 
and  the  quantity  of  air  tested  being  known  by  deducting 
the  amount  of  stock  lime-water  introduced  into  the  bottle 
from  its  total  capacity,  which  has  been  already  found  by 
measuring  the  quantity  of  water  it  will  hold,  the  percentage 
of  carbon  dioxide  in  the  air  examined  is  readily  determined. 

Example:  Suppose  that  25  c.c.  of  stock  lime-water 
requires  30  c.c.  acid  solution  and  25  c.c.  of  lime-water 
from  the  bottle  requires  27  c.c.  of  acid  solution. 


518     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

Therefore  30  c.c  — 27  e.c.=  3  c.c.=  amount  of  carbon 
dioxide  that  was  in  the  air  in  the  bottle,  which  latter  con- 
tains (for  example,  say)  2550  c.c.  when  exactly  filled. 

^,        3X100        300    •    ,„  ^        ,        ,.    ., 

Ihen  T^^ri^ ^  =  ^^777;  =  0.12  per  cent,  carbon  dioxide 

zoou  —  50      2500 

in  the  tested  air  at  current  temperature  and  pressure.    To 

be  absolutely  exact  in  the  result,  correction  must  be  made 

by  bringing  the  air  volume  to  the  standard  temperature 

(0°  C.)  and  barometric  pressure  (760  mm.),  but  this  is 

unnecessary  in  most  cases. 

The  phenolphthalein  "indicator"  is  made  by  dissolving 

0.5  gramme  of  phenolphthalein  in  100  c.c.  of  alcohol. 

WATER. 

To  test  for  color,  turbidity,  etc.,  compare  with  distilled 
water,  using  tall  glass  jars  and  looking  down  through 
equal  depths  upon  a  white  surface.  The  smell  of  a  water 
may  be  detected  by  heating  it  to  about  140°  F.  for  a  few 
minutes  in  a  glass-stoppered  bottle.  This  test  may  or 
may  not  indicate  fecal  contamination.  Few  polluting 
impurities,  when  only  in  moderate  quantities,  give  any 
taste  to  water,  and  a  dangerously  polluted  water  may 
have  a  good  taste.  Iron  in  small  quantities,  one-fourth 
of  a  grain  to  a  gallon,  will  give  a  taste  to  the 
water. 

Use  caution  in  tasting  suspicious  waters.  Aeration  is 
indicated  by  the  lustre  of  the  water  and  by  the  presence 
of  air-bubbles  on  the  sides  and  bottom  of  the  vessel. ^ 

Test  for  Chlorin. — Solutions  required:  (1)  Standard 
nitrate  of  silver  solution :  to  1  liter  of  pure  distilled  water 
add  4.788  grammes  of  pure  silver  nitrate;  1  c.c.  of  this 
solution  is  equivalent  to  1  mg.  of  chlorin.  (2)  Potas- 
sium chromate  solution — a  5  or  10  per  cent,  solution  of 
potassium  chromate  made  up  in  distilled  water  free  from 
chlorin. 

1  See  also  pages  222  to  228. 


TEST  FOR  CHLORIN 


519 


Process, — To  100  c.c.  of  the  water  add  from  0.5  to  1  c.c. 
of  potassium  chromate  solution,  and  then  run  in  from  a 
burette  or  graduated  pipette  the  standard  silver  solution, 
adding  it  drop  by  drop,  and  stirring 
the  water  with  a  glass  rod.  Continue 
until  a  faint  but  permanent  orange- 
red  tint  has  been  produced,  showing 
that  all  the  chlorin  has  combined 
with  the  silver,  the  persistent  reddish 
color  being  due  to  silver  chromate. 
The  number  of  c.c.  of  silver  solution 
used  indicates  the  number  of  milli- 
grammes of  chlorin  in  100  c.c,  or 
parts  per  100,000;  this  multiplied  by 
10  gives  the  number  of  milligrammes 
in  1  liter,  or  parts  per  1,000,000.  If 
the  water  contains  but  little  chlorin, 
accuracy  will  be  furthered  by  evapo- 
rating 250  c.c.  of  the  water  to  50  c.c. 
over  a  water-bath,  and  proceeding 
as  above;  the  result  multiplied  by  4 
wdll  give  the  amount  of  chlorin  in  1 
liter.  On  the  other  hand,  if  the  water 
contains  much  chlorin,  the  test  will 
be  facilitated  by  using  50  c.c.  or  even 
25  c.c.  of  the  sample,  adding  a  corre- 
spondingly smaller  quantity  of  the 
potassium  chromate  indicator. 

Water  containing  much  organic  col- 
oring matter  or  iron  should  be  decolor- 
ized before  making  the  above  test  by 
adding  from  3  to  5  c.c.  of  milk  of  alu- 
mina, free  from  chlorides,  to  about 
half  a  liter  of  the  water,  heating  to 
boiling  and  filtering. 

Test  for  Nitrates. — Solutions  required:  (1)  Phenol- 
sulphonic  acid:  6  grammes  of  pure  carbolic  acid;  37  c.c. 
of  strong  sulphuric  acid,  and  3  c.c.  of  distilled  water.    (2) 


Fig.  155.— Bottle  for 
collecting  samples  of 
water  at  different 
levels. 


520     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

Standard  potassium  nitrate  solution:  add  0.722  gramme 
of  fused  potassium  nitrate  to  1  liter  of  distilled  water. 
Each  c.c.  of  this  solution  contains  0.1  mg.  of  nitrogen  as 
nitrates.  The  water  used  in  making  the  solution  must  be 
free  from  nitrates. 

Process. — Evaporate  10  c.c.  of  the  water  to  be  exam- 
ined (or  25  c.c.  if  it  is  presumably  low  in  nitrates)  just  to 
dryness  in  a  small  and  clean  porcelain  dish.  Add  1  c.c. 
of  phenolsulphonic  acid,  stir  with  a  glass  rod,  and  add 
1  c.c.  of  distilled  water  and  3  drops  of  strong  sulphuric 
acid;  warm,  and  dilute  well  with  distilled  water;  then 
add  ammonia  until  the  fluid  is  strongly  alkaline,  and 
dilute  with  water  to  50  c.c.  Be  careful  throughout  the 
test,  but  especially  when  evaporating,  not  to  dissociate 
and  drive  off  any  of  the  nitrates  by  too  prolonged  or 
intense  heating. 

Treat  1  c.c.  of  the  standard  solution  in  an  exactly 
similar  manner  and  compare  the  tints  produced,  placing 
the  resulting  solutions  in  two  Nessler  or  other  tubes  of 
equal  caliber,  and  diluting  the  more  intense  until  the  tints 
match  exactly;  then  calculate  the  amount  of  nitrogen 
present  by  the  amount  of  dilution  necessary — e.  g.,  sup- 
pose that  in  testing  a  certain  sample,  the  tint  from  1  c.c.  of 
standard  potassium  nitrate  solution  is  darker  and  requires 
the  addition  of  50  c.c.  more  water — i.  e.,  up  to  100  c.c.  to 
match  the  tint  of  the  tested  sample.  Therefore  100  c.c. 
:  50  c.c.  :  :  0.1  mg.  N  :  x  =0.05  mg.,  the  amount  of  nitrogen 
as  nitrates  in  the  10  c.c.  of  water  examined.  The  propor- 
tion would  be  reversed,  of  course,  if  the  water  tested  had 
the  stronger  tint.  The  test  is  based  on  the  facts  that 
some  of  the  phenolsulphonic  acid  is  converted  by  the 
nitrates  into  picric  acid,  which  forms  ammonium  picrate 
upon  addition  of  the  ammonia  and  gives  a  yellow  tint 
to  the  water,  and  that  the  amount  of  picric  acid  and  picrate 
formed  and  the  consequent  depth  of  color  depend  on  the 
amount  of  nitrates  present  in  the  water. 

"The  accuracy  of  this  test  is  diminished  by  the  presence 
of  chlorides  in  notable  amounts,  say  more  than  2  parts 


TEST  FOR  NITRATES  521 

in  100,000,  but  not  by  nitrites.  On  this  account,  Mason 
recommends  the  addition  of  corresponding  amounts  of 
sodium  chloride  in  the  preparation  of  the  color  scale."^ 

Test  for  Nitrites. — Solutions  required:  (1)  Sulphanilic 
acid:  dissolve  0.5  gramme  of  sulphanilic  acid  in  150  c.c. 
of  dilute  acetic  acid,  sp.  gr.  104.  (2)  Naphthylamine 
acetate:  boil  0.1  gramme  of  solid  naphthylamine  in 
20  c.c.  of  distilled  water,  filter  through  a  plug  of  washed 
absorbent  cotton,  and  mix  the  filtrate  with  180  c.c.  of 
dilute  acetic  acid.  (3)  Standard  sodium  nitrite  solution: 
dissolve  0.275  gramme  of  pure  silver  nitrite  in  pure  water 
and  add  a  dilute  solution  of  pure  sodium  chloride  until  a 
precipitate  ceases  to  form,  and  dilute  to  250  c.c.  with  pure 
water.  For  use,  dilute  10  c.c.  of  this  stock  solution  to 
100  c.c.  Each  c.c.  of  the  dilute  solution  contains  0.01  mg. 
of  nitrogen  as  sodium  nitrite.  Keep  both  solutions  in  the 
dark  when  not  in  use,  preferably  in  amber  bottles.  All 
water  in  these  solutions  must  be  free  from  nitrites;  like- 
wise all  water  used  in  the  tests,  except  the  sample  under 
examination. 

Process. — Place  25  c.c.  of  the  water  to  be  examined  in 
a  cylindrical  vessel,  and  in  a  similar  vessel  of  the  same 
caliber  dilute  1  c.c.  of  the  (diluted)  standard  sodium  nitrite 
solution  to  25  c.c.  with  nitrogen-free  distilled  water;  add 
to  each  vessel  2  c.c.  of  first  one  and  then  the  other  reagent, 
using  a  separate  pipette  for  each.  "If  nitrites  are  present 
(in  the  w^ater  tested)  a  pink  to  a  garnet  color  is  developed 
within  half  an  hour,  the  intensity  of  color  depending  upon 
the  amount  of  nitrite  present.  Since  the  air  of  laboratories 
in  which  gas  is  burning  is  very  likely  to  contain  traces 
of  nitrites,  which  are  absorbed  readily  by  water,  it  is 
well  to  keep  the  tubes  corked  or  otherwise  protected."^ 
Compare  the  colors  at  the  end  of  half  an  hour,  or  sooner  if 
the  tints  seem  permanent,  and  estimate  the  amount  of 
nitrites  by  diluting  the  darker  tint  until  it  matches  the 
lighter,  and  comparing  the  respective  volumes,  as  in  the 

*  Harrington,  Practical  Hygiene,  5th  ed.,  p.  463. 
« Ibid.,  p.  462. 


522     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

test  for  nitrates;  the  result  will  give  the  quantity  of 
nitrogen  as  nitrites  in  the  water,  and  should  not  be  more 
than  a  trace.    The  above  test  is  a  very  delicate  one. 

Schuyten's  Method} — "When  5  c.c.  of  a  1  per  cent, 
solution  of  antipyrin  in  acetic  acid  (1  to  10)  is  added  to  a 
solution  containing  nitrites,  a  green  color  is  produced.'^ 
Measure  45  c.c.  of  the  water  to  be  examined  into  a 
Nessler  tube,  and  in  another  of  equal  caliber  mix  1  c.c. 
of  the  standard  sodium  nitrite  solution  (dilute)  with 
44  c.c.  of  distilled  and  nitrite-free  water.  To  each  tube 
add  5  c.c.  of  the  antipyrin  solution.  Allow  to  stand  for 
one-half  hour  and  compare  as  above. 

"This  method  will  show  the  presence  of  1  part  of 
nitrogen  as  nitrous  oxide  in  20,000  parts,  and  while  not 
so  delicate  as  the  other  method,  is  not  hindered  by  the 
presence  of  any  of  the  ordinary  contaminations  in  water.  "^ 

Test  for  Free  and  Albuminoid  Ammonia. — Wanklyn^s 
Method. — Solutions  required:  (1)  Standard  ammonium 
chloride  solution:  dissolve  0.382  gramme  of  pure  dry 
ammonium  chloride  in  100  c.c.  of  ammonia-free  water. 
For  immediate  use  dilute  10  c.c.  of  this  standard  stock 
solution  up  to  100  c.c.  with  ammonia-free  water;  each 
c.c.  of  the  dilute  solution  contains  0.01  mg.  of  nitrogen 
as  ammonia.  (2)  Alkaline  potassium  permanganate  solu- 
tion: dissolve  200  grammes  of  potassium  hydrate  (in 
sticks)  and  8  grammes  of  potassium  permanganate  in  1 
liter  of  distilled  water,  evaporate  to  about  750  c.c.  to 
drive  off  the  ammonia  present,  and  make  up  to  1  liter 
again  with  ammonia-free  water.  To  make  ammonia-free 
water,  add  about  1  gramme  of  sodium  carbonate  to  1  liter  of 
distilled  water  and  boil  until  about  one-fourth  is  evapo- 
rated. (3)  Nessler's  reagent:  dissolve  1.5  grammes  of 
potassium  iodide  in  10  c.c.  of  distilled  water  and  1.7 
grammes  of  mercuric  chloride  (HgCW  in  30  c.c.  of  dis- 
tilled water;  add  the  mercuric  chloride  solution  to  the 
potassium  iodide  until  a  permanent  precipitate  is  formed, 

^  Bergey's  Hand-book  of  Practical  Hygiene,  p.  95.  ^  ibid. 


TESTS  FOR  NITRITES  AND  AMMONIA         523 

and  then  dilute  to  100  c.e.  witli  a  20  per  cent,  solution  of 
sodium  hydrate,  add  the  mercuric  chloride  solution  until 
a  permanent  precipitate  again  forms,  and  allow  to  stand 
until  clear;  this  reagent  gives  a  brown  or  yellowish-brown 
coloration  if  ammonia  be  present  in  water,  and  improves 
on  keeping. 

Process. — Place  in  a  retort  500  c.c.  of  the  water  to  be 
examined,  connect  with  a  condenser,  and  boil  gently 
so  that  the  water  may  distil  over  slowly.     The  retort 


Fig.  156. — Distilling  apparatus  used  in  determining  the  ammonias  in 
water.     (Harrington.) 

and  condenser  should  have  been  thoroughly  rinsed  with 
ammonia-free  water.  Collect  the  distillate,  50  c.c.  at  a 
time,  in  Nessler  tubes  matched  as  to  caliber,  add  2  c.c. 
of  Nessler's  reagent  to  each  50  c.c,  and  determine  the 
amount  of  ammonia  or  nitrogen  in  each  as  follows:  Place 
in  another  Nessler  tube  of  the  same  caliber  a  little  less 
than  50  c.c.  of  ammonia-free  water  and  2  c.c.  of  Nessler's 
reagent,  run  in  from  a  burette  the  dilute  standard  ammo- 
nium chloride  solution  until  the  color  exactly  matches  that 
of  the  first  50  c.c.  of  the  distillate,  taking  care  to  bring 


524     EXAMINATION  OF  AIR,   WATER,   AND  FOOD 

the  fluid  to  the  same  level  in  the  two  tubes  by  the  addition 
of  ammonia-free  water  to  one  or  the  other.  Repeat  the 
process  for  each  50  c.c.  of  distillate  until  the  test  shows 
no  more  ammonia  is  coming  over  from  the  retort.  The 
total  amount  of  (dilute)  ammonium  chloride  solution  used 
indicates  the  total  amount  of  nitrogen  of  the  free  ammonia. 
Usually  all  the  free  ammonia  will  come  over  in  the  first 
150  or  200  c.c.  of  distillate.  Compare  the  colors  by  looking 
down  through  the  tubes  on  a  white  surface.  Some  waters 
yield  so  much  ammonia  in  the  first  50  c.c.  of  distillate  that 
a  precipitate  is  formed  upon  the  addition  of  the  Nessler 
reagent.  In  such  case  the  process  should  be  repeated  with 
a  new  500  c.c.  of  the  water  to  be  examined  and  one-half  or 
even  lesser  fraction  of  the  first  50  c.c.  distilled  should  be 
taken  and  diluted  to  that  volume  with  ammonia-free  water 
before  adding  the  reagent.  Or  all  of  the  distillates  may 
be  mixed  together,  50  c.c.  of  this  mixture  taken,  treated 
with  the  reagent  and  its  content  of  ammonia  determined 
by  matching  its  color  against  that  produced  in  another 
tube  by  the  standard  ammonium  chloride  solution  used 
as  above.  This  result  must,  of  course,  be  multiplied  by 
the  proper  multiple  to  indicate  the  amount  of  free  ammo- 
nia in  the  total  distillate.  The  free  ammonia  being  deter- 
mined, allow  the  retort  to  cool  and  add  to  the  water 
remaining  in  it  50  c.c.  of  the  alkaline  permanganate 
solution.  This,  when  heated,  converts  a  certain  propor- 
tion of  the  nitrogenous  organic  matter  of  the  water  into 
ammonia.  Distil  as  before,  estimating  the  amount  of 
nitrogen  in  each  50  c.c.  of  the  distillate  until  ammonia 
ceases  to  come  over.  The  amount  of  ammonium  chloride 
solution  thus  used  will  indicate  the  nitrogen  of  albuminoid 
ammonia,  and  the  total  amount  of  ammonium  chloride 
solution  used  in  the  whole  process  gives  the  nitrogen  of  the 
total  free  and  albuminoid  ammonia  in  one-half  liter  of  water. 
Test  for  Hardness. — Solutions  required:  (1)  Soap  solu- 
tion: dissolve  10  grammes  of  old,  dry  castile  soap,  free 
from  sodium  carbonate  and  hydrate,  in  1  liter  of  weak 
(60  per  cent.)  alcohol.     (2)  Standard  lime  solution:  dis- 


TEST  FOR  FREE    AND  ALBUMINOID  AMMONIA      525 

solve  1.11  grammes  of  chemically  pure  calcium  chloride 
in  1  liter  of  distilled  water:  1  c.c.  of  this  solution  is  equiva- 
lent to  1  mg.  of  calcium  carbonate. 

Process. — Ascertain  how  much  soap  solution  is  required 
to  make  a  standard  lather  with  100  c.c.  of  distilled  water, 
as  follows:  Place  the  water  in  a  flask  holding  about 
250  c.c,  and  run  in  the  soap  solution  from  a  burette,  a  few 
drops  at  a  time,  corking  and  shaking  the  flask  well  after 
each  addition;  the  lather  should  be  made  up  of  small 
bubbles,  have  a  depth  of  at  least  one-fourth  of  an 
inch  and  be  permanent  for  at  least  two  minutes.  Then 
standardize  the  soap  solution  by  diluting  5  c.c.  of  the 
standard  lime  solution  to  100  c.c.  with  distilled  water, 
and  determine  how  many  c.c.  of  the  soap  solution  are 
required  to  make  a  permanent  lather  as  above  with  it; 
this  quantity,  less  the  number  of  c.c.  needed  to  make  a 
lather  with  100  c.c.  of  distilled  water,  represents  the 
amount  of  soap  solution  that  will  neutralize  5  mg.  of 
calcium  carbonate  or  its  equivalent.  Lastly,  determine 
in  the  same  way  the  number  of  c.c.  of  soap  solution  neces- 
sary to  make  a  permanent  lather  with  100  c.c.  of  the  water 
to  be  examined;  again  subtract  the  quantity  of  soap 
solution  requisite  to  make  a  lather  with  100  c.c.  of  dis- 
tilled water,  and  estimate  the  amount  of  calcium  carbonate 
or  its  equivalent  present,  as  follows — e.  g.,  it  takes  2  c.c. 
of  soap  solution  to  make  a  lather  with  the  distilled  water, 
and  12  c.c.  with  the  diluted  standard  lime  solution; 
then  12  c.c.  —  2  c.c.  =  10  c.c,  which  is  equivalent  to 
5  c.c  of  the  standard  lime  solution,  and  accordingly  each 
c.c.  of  the  soap  solution  is  equivalent  to  0.5  c.c.  of  the 
standard  lime  solution,  or  to  0.5  mg.  of  calcium  car- 
bonate; consequently,  if  100  c.c.  of  the  water  examined 
require  17  c.c  of  soap  solution,  it  must  contain  (17  —  2) 
X  0.5=  7.5  mg.  of  calcium  carbonate  or  its  equivalent, 
or  75  mg.  to  the  liter.  This  test  is  not  exactly  accurate, 
since  there  is  a  gradual  lessening  in  the  amount  of  soap 
solution  needed  as  the  amount  of  lime  increases.  A  better 
method,  if  time  permits,  is  to  dilute  from  1  to  10  cc  of 


526     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

the  standard  calcium  chloride  solution  successively  to 
100  c.c,  testing  each  dilution  with  the  soap  solution  as 
above  and  thus  making  a  scale  to  which  the  amount  of 
soap  solution  needed  for  the  sample  water  may  be  referred. 
If  the  sample  water  shows  a  hardness  greater  than  that 
indicated  by  10  c.c.  of  the  standard  calcium  chloride 
solution,  a  fractional  part  of  100  c.c.  of  the  water  may  be 
diluted  up  to  that  amount  with  distilled  water  and  the 
test  repeated,  making  a  proper  calculation  later  for  the 
amount  used. 

Tests  for  Lead,  Copper,  and  Iron. — To  50  or  100  c.c. 
of  water  in  a  white  porcelain  dish,  or  in  a  tall  glass  jar 
over  white  paper,  add  a  few  drops  of  ammonium  sul- 
phide; a  dark  coloration  or  precipitate  indicates  the  pres- 
ence of  either  lead,  copper,  or  iron,  due  to  formation  of 
their  respective  sulphides.  If  only  small  quantities  of 
one  or  more  of  the  metals  are  present,  it  may  be  neces- 
sary to  concentrate  the  water  by  boiling  in  order  to 
secure  the  reaction.  It  should  be  remembered  that  the 
ammonium  sulphide  gives  some  color  and  that  the  later 
addition  of  acid  may  also  cause  some  turbidity.  Then 
add  a  few  drops  of  hydrochloric  acid:  if  the  color  disap- 
pears, iron  only  is  present;  if  it  persists,  lead  or  copper 
is  present.  In  the  latter  case  add  a  few  drops  of  acetic 
acid  and  about  1  c.c.  of  a  strong  solution  of  potassium 
cyanide:  if  the  color  disappears,  it  is  due  to  copper;  if 
it  persists,  it  is  due  to  lead.  If  lead  only  is  present,  the 
above  test  should  detect  one-tenth  of  a  grain  per  gallon. 
The  above  tests  may  be  corroborated  as  follows:  Partly 
fill  two  test-tubes  with  the  original  water.  To  one  add 
a  little  potassium  chromate  solution:  a  turbidity  and  the 
deepening  of  the  color  to  canary-yellow  indicate  lead. 
Harvey  claims  that  0.3  milligramme  of  lead  in  1  liter  of 
water  "will  show  a  turbidity  from  chromate  when  250  c.c. 
are  treated  with  0.1  gramme  of  potassium  bichromate, 
and  that  in  twelve  hours  the  precipitate  will  settle  and 
become  still  more  distinct."^  To  the  second  test-tube 
add  a  drop  of  hydrochloric  acid  and  a  few  drops  of  potas- 


TESTS  FOR  LEAD,  COPPER,  AND  IRON         527 

Slum  ferrocyanide  solution:  a  blue  color  indicates  iron, 
in  either  the  ferrous  or  ferric  form ;  a  bronze  or  mahogany- 
red  color  indicates  copper. 

Quantitative  tests  for  the  above  metals  may  be  made  by 
making  standard  solutions  of  the  respective  elements  or 
some  of  their  salts,  treating  a  measured  quantity  of  the 
original  water  with  the  proper  reagent  as  indicated  above, 
and  comparing  the  color  produced  with  that  given  by  a 
definite  quantity  of  the  respective  standard  solution. 

Test  for  Phosphates. — Solutions  required:  Ammonium 
molybdate:  dissolve  10  grammes  of  molybdic  anhydride 
in  41.7  c.c.  of  ammonia  (sp.  gr.,  0.96)  and  pour  slowly 
into  125  c.c.  of  nitric  acid  (sp.  gr.,  1.20);  allow  to  stand 
in  a  warm  place  for  several  days  until  clear. 

Process. — Slightly  acidulate  500  c.c.  of  water  with 
nitric  acid,  evaporate  to  50  c.c,  and  add  a  few  drops  of 
ferric  chloride  and  ammonia  to  slight  excess;  filter,  dis- 
solve the  precipitate  in  the  smallest  possible  quantity  of 
nitric  acid  and  evaporate  to  5  c.c. ;  heat  nearly  to  boiling, 
add  20  c.c.  of  ammonium  molybdate  solution;  keep  the 
solution  warm  for  one-half  hour.  If  there  is  an  appreci- 
able quantity  of  precipitate,  collect  it  on  a  small,  weighed 
filter-paper,  wash  with  distilled  water,  dry  at  100°  F.,  and 
weigh.  The  weight  of  the  precipitate  multiplied  by  0.05 
gives  the  amount  of  phosphorus  tetroxide  (PO4)  in  the 
500  c.c.  of  water. 

The  importance  and  relative  value  of  the  results  of  the 
foregoing  tests  in  determining  the  purity  or  safety  of  a 
drinking-water,  have  been  given  in  Chapter  V  on  pages 
225  to  228,  inclusive. 

FOOD. 

Milk. —  Good  Milk.  —  Characteristics:  ivory  white, 
opaque,  neutral  or  slightly  alkaline  reaction,  no  sediment, 
no  unusual  or  offensive  taste  or  odor,  specific  gravity,  1.029 

1  Harrington,  loc.  cit.,  p.  469. 


528     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

or  above;  cream,  10  to  40  per  cent,  by  volume;  fats,  3 
per  cent,  or  more;  total  solids,  12.5  per  cent,  or  more. 

Water  is  indicated  by  low  specific  gravity  and  by  low 
percentage  of  cream. 

Skimming  is  indicated  by  a  slightly  raised  specific 
gravity  (2°),  by  a  low  percentage  of  cream,  and  by  a 
poor  color,  though  the  deterioration  in  color  may  be  dis- 
guised by  the  addition  of  annatto,  etc. 

Watering  and  skimming  are  indicated  by  lowered 
specific  gravity,  by  low  percentage  of  cream,  and  by 
poor  color. 

The  specific  gravity  is  determined  by  the  lactometer, 
or  lactodensimeter,  in  using  which  correction  must  be 
made  for  temperature,  provided  the  latter  varies  much 
from  60°  F.,  the  standard. 

The  percentage  of  cream  is  determined  by  the  cream 
gauge  or  creamometer;  the  milk  should  be  allowed  to 
stand  in  the  creamometer  for  at  least  eight  to  ten  hours, 
and  should  be  covered. 

A  very  high  percentage  of  cream  tends  to  lower  the 
sp'ecific  gravity  theoretically;  but  when  a  milk  is  rich  in 
fat  it  is  also  rich  in  solids  not  fat. 

An  acid  reaction,  unless  very  slight,  indicates  souring 
of  the  milk  or  the  addition  of  some  preserving  acid.  A 
strongly  alkaline  reaction  indicates  the  addition  of  some 
substance  like  chalk,  sodium  carbonate,  etc.,  to  increase 
the  specific  gravity.  Such  addition  is  verified  by  an 
excess  of  total  solids,  and  by  the  effervescence  of  the  latter 
— after  drying — upon  the  addition  of  a  drop  or  two  of 
hydrochloric  acid. 

To  determine  the  percentage  of  total  solids:  Weigh  a 
small  evaporating  dish, '  preferably  platinum,  add  5  to 
10  c.c.  of  milk,  and  weigh  dish  and  milk  to  get  weight  of 
milk;  evaporate  to  dryness  over  a  water-bath,  completing 
the  drying  in  a  water-oven  until  there  is  no  further  loss 
of  weight;  weigh  dish  and  contents  (total  solids);  sub- 
tract weight  of  dish,  multiply  by  100,  and  divide  by 
weight  of  milk.    Result:    the  percentage  of  total  solids. 


MILK 


529 


To  determine  the  percentage  of  ash:     Ignite  the  total 
solids  over  a  naked  flame  until  all  black  specks  have 


Fio.  157. — Lactodensimcter. 
(Harrington.) 


Fio.  158. — Bottle  for  determin- 
ing percentage  of  fat  by  means  of 
the  centrifuge. 


disappeared;  cool  and  weigh;  multiply  weight  of  ash  by 
100,  and  divide  by  weight  of  milk.    Result:    percentage 
of  ash. 
34 


530     EXAMINATION  OF  AIR,  WATER,  AND  FOOD 

To  determine  the  percentage  of  fats:  Proceed  as  above 
with  10  c.c.  of  milk,  and  evaporate  until  the  residue  is  a 
tenacious  pulp,  extinguish  the  flame,  fill  the  dish  half- 
full  of  ether,  stir  and  triturate  the  residue  thoroughly  with 
a  glass  rod,  decant  the  ether  and  filter  it  through  a  small 
filter-paper,  reserving  the  filtrate;  add  more  ether  to  the 
residue,  stir  and  triturate  as  before,  and  filter,  repeating 
the  process  three  times  or  until  the  residue  is  perfectly 
white;  wash  the  filter-paper  well  with  ether,  collect  the 
latter  and  add  to  the  preceding  filtrate;  evaporate  the 
ether  filtrate  until  only  the  fat  remains  and  its  weight  is 
constant;  weigh  the  fat,  multiply  by  100,  and  divide  by 
the  weight  of  the  milk.    Result:    percentage  of  fat. 

This  method  when  carefully  performed  is  said  to  be 
fully  as  accurate  as  the  extraction  (Soxhlet)  method,  and 
does  not  require  the  more  expensive  apparatus  of  the 
latter.  If  the  residue  from  which  the  fat  has  been 
exhausted  is  carefully  dried  on  a  water-bath  at  100°  C. 
until  there  is  no  further  loss  by  evaporation,  its  weight 
will  be  that  of  the  "solids  not  fat"  of  the  milk. 

Centrifugal  method:  Where  a  centrifuge  is  available  for 
use,  the  following  method  for  the  fat-determination  will 
be  found  to  give  results  that  are  probably  accurate  to 
within  0.2  per  cent,  of  fat: 

Two  solutions  are  necessary:  (1)  Fusel  oil,  37  c.c; 
wood  or  methyl  alcohol,  13  c.c;  hydrochloric  acid,  50  c.c 
(2)  Sulphuric  acid,  sp.  gr.,  1.83. 

Into  the  milk  bottle  (Fig.  158),  which  is  made  to  fit 
the  centrifuge  and  which  has  a  long,  graduated  neck, 
5  c.c  of  the  milk  to  be  examined  are  introduced  by  means 
of  a  pipette,  and  to  this  1  c.c.  of  the  alcohol  solution 
(1)  is  added  and  the  mixture  well  shaken  by  hand.  The 
sulphuric  acid  is  then  added,  little  by  little,  with  frequent 
shaking,  until  the  bottle  is  filled  to  the  topmost  (zero) 
graduation.  It  is  then  rapidly  whirled  in  the  centrifuge 
until  only  the  fat  occupies  the  neck  as  a  clear  layer,  when 
the  actual  percentage  can  be  read  from  the  graduations. 
When  the  milk  is  very  rich — i.  e.,  containing  more  than 


DETERMINATION  OF  FAT  IN  MILK 


531 


5  per  cent,  of  fat — it  will  be  necessary  to  dilute  the  milk 
with  an  equal  volume  of  water,  and  then  to  multiply  the 


Fig.  159. — Meeker  tube  for  test- 
ing milk  in  centrifuge. 


Fio.  160. — Soxhlet  extraction 
apparatus.    (Harrington.) 


532     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

result  by  2.  Likewise,  cream  should  be  diluted  with  4 
parts  of  water  and  the  result  multiplied  by  5.  The  same 
principle  is  employed  in  the  Babcock  and  other  cream- 
testers  now  largely  used  by  dairymen,  etc. 

A  somewhat  simpler  method  has  been  devised  by 
Prof.  Meeker,  in  which  the  only  reagent  is  sulphuric 
acid,  sp.  gr.  1.83,  and  a  tube  of  different  form  (Fig.  159) 
is  used.  Into  this  tube  the  milk  is  introduced  from  a 
pipette  holding  exactly  8.8  c.c,  and  having  a  long  delivery 
end  to  carry  the  milk  beyond  the  constricted  and  grad- 
uated portion.  The  sulphuric  acid  is  then  added  in  equal 
volume,  filling  the  tube  to  the  zero  mark,  after  which 
the  stopper  is  inserted  and  the  milk  and  acid  thoroughly 
mixed  by  inverting  and  reinverting  the  tube.  This 
breaks  up  the  casein  of  the  milk  and  frees  the  fat,  which 
will  collect  in  the  graduated  part  when  the  tube  is  whirled 
in  the  centrifuge.  Owing  to  cooling,  there  may  be  a  slight 
contraction  of  the  liquid,  and  the  top  may  be  slightly 
below  the  zero  mark,  so  it  is  well  to  again  warm  the  milk 
by  immersing  the  tube  in  hot  water,  and  to  give  a  second 
whirling  for  but  a  moment  or  two.  The  percentage  of 
fat  is  indicated  by  the  difference  of  the  reading  of  its 
upper  and  lower  limits. 

The  extraction  method:'^  "About  10  grammes  of  milk 
are  carefully  weighed  in  a  glass  or  porcelain  capsule  and 
mixed  with  about  10  grammes  of  freshly  ignited  sand, 
pumice-stone,  or  asbestos,  and  evaporated  to  dryness  on 
a  water-bath.  The  dish  with  its  contents  is  then  finely 
pulverized  and  transferred  to  a  Soxhlet  extraction  appa- 
ratus and  the  fat  extracted  with  ether  for  at  least  five 
hours.  The  ether  extract  of  the  fat  is  then  evaporated  to 
dryness  on  a  water-bath  and  the  residue  dried  to  constant 
weight  (at  100°  C.)  and  weighed.  The  increased  weight 
of  the  flask  (of  the  Soxhlet  apparatus)  will  represent  the 
fat  in  the  10  grammes  of  milk." 

A  Soxhlet  apparatus  is  so  constructed  that  a  quantity 

1  Bergey's  Hand-book  of  Practical  Hygiene,  p.  129. 


CENTRIFUGAL  AND  EXTRACTION  METHODS     533 

of  ether  is  repeatedly  evaporated  and  condensed  in  it 
without  loss,  the  condensed  ether  being  made  to  percolate 
through  substances  placed  in  the  upper  part  of  the  appa- 
ratus and  to  extract  therefrom  soluble  matters,  such  as 
fat,  which  are  collected  in  a  small  flask  below,  and  from 
which  the  ether  can  finally  be  evaporated. 

Test  for  annatto:  A  percentage  of  cream  considerably 
lower  than  the  color  of  the  milk  would  indicate  justifies 
the  suspicion  that  some  coloring-matter  has  been  used. 
This  is  frequently  annatto. 

"To  about  100  c.c.  of  milk  in  a  cylinder  add  a  few  cubic 
centimeters  of  sodium  carbonate  solution  to  insure  a 
strongly  alkaline  reaction  during  the  examination,  and 
then  introduce  a  strip  of  heavy  white  filter-paper  about 
0.5  by  5.5  inches,  and  set  the  whole  away  in  a  dark  place 
over  night.  If  any  annatto  color  is  present,  it  will,  through 
selective  affinity,  pass  from  the  milk  to  the  fiber  of  the 
paper,  which  thereby  acquires  a  salmon  tint,  the  depth 
of  which  is  dependent,  naturally,  upon  the  amount  of 
substance  present.  The  strip  is  withdrawn  from  the 
milk,  washed  gently  in  running  water,  and  laid  upon  a 
piece  of  paper  of  the  same  kind  as  itself.  If  so  much  as 
1  part  of  the  annatto  solution  in  100,000  is  present,  the 
strip  will  show  a  distinct  salmon  tint.  On  dipping  the 
strip  into  stannous  chloride  solution  the  color  is  changed 
to  pink."^ 

Test  for  boric  acid:  Upon  igniting  the  total  solids, 
boric  acid  or  boron  gives  a  greenish  tinge  to  flame.  Place 
in  a  porcelain  dish  5  c.c.  of  milk,  1  drop  of  strong  hydro- 
chloric acid,  and  2  drops  of  a  saturated  tincture  of  tur- 
meric. Dry  on  a  water-bath,  remove  as  soon  as  dry; 
cool,  and  add  1  drop  of  ammonia  on  a  glass  rod.  A  slaty- 
blue  color,  changing  to  green,  is  given  if  borax  is  present. 
This  test  will  show  tdVit  grain  of  borax.  Less  will  give 
the  green  color,  but  not  the  blue. 

Test  for  salicylic  acid  and  salicylates  (Bergey) :  Dilute 
the  milk  (100  c.c.)  with  an  equal  bulk  of  distilled  water 

^  Harrington,  Practical  Hygiene.  5th  ed.,  p.  168. 


534     EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

at  60°  C;  precipitate  with  8  drops  of  acetic  acid  and  8 
drops  of  a  solution  of  mercuric  oxide  in  nitric  acid;  shake 
and  filter.  To  the  filtrate  add  50  c.c.  of  ether,  which 
takes  up  the  salicylic  acid;  decant,  and  filter  the  super- 
natant ether.  Evaporate  this  filtrate  nearly  to  dryness, 
and  add  a  few  drops  of  highly  diluted  neutral  ferric 
chloride.  A  violet  color  indicates  the  presence  of  salicylic 
acid,  the  depth  of  color  increasing  with  the  amount. 

To  test  for  salicylic  acid  in  butter,  it  is  first  treated 
with  sodium  carbonate  and  the  homogeneous  mixture 
acidulated  with  sulphuric  acid,  and  then  shaken  with  a 
mixture  of  equal  parts  of  ether  and  petroleum  ether,  after 
which  the  supernatant  ether  is  filtered  off  and  treated  as 
above. 

Ted  for  formaldehyde  (Bergey) :  Add  an  equal  volume 
of  water  to  the  milk  or  butter  to  be  tested,  place  in  a  flask 
on  a  steam-bath  and  distil  over  about  one-fourth  the  total 
volume.  Treat  10  c.c.  of  the  distillate  with  2  drops 
of  ammoniacal  silver  solution  (made  by  dissolving  1 
gramme  of  silver  nitrate  in  30  c.c.  of  distilled  water 
and  adding  ammonia  until  the  precipitate  that  first  appears 
is  redissolved,  then  diluting  to  50  c.c.  with  water).  If 
formaldehyde  is  present,  it  causes  a  black  cloud  in  the 
distillate  after  standing  for  several  hours  in  the  dark. 

Harrington  gives  the  following  test  among  others: 
''Mix  in  a  porcelain  dish  10  c.c.  each  of  milk  and  hydro- 
chloric acid  (sp.  gr.,  1.2)  and  1  drop  of  ferric  chloride 
solution.  Heat  and  stir  vigorously.  If  formalin  has 
been  added,  a  violet  color  will  appear  before  the  boiling- 
point  has  been  reached,  varying  in  intensity  according 
to  the  amount  present.  This  process  is  exceedingly  deli- 
cate and  will  detect  1  part  in  500,000  in  the  fresh  condi- 
tion."i 

According  to  Hehner,  "no  formaldehyde  could  be 
detected  at  the  end  of  a  week  in  a  sample  (of  milk)  to  which 
had  been  added  1  part  in  100,000;  after  two  weeks  none 
could  be  detected  in  a  sample  of  1  part  in  50,000;  and 

1  For  other  tests  for  formaldehyde  see  Harrington,  5th  ed.,  pp.  170 
and  171;  and  Leffmann  and  Sevan's  Food  Analysis,  pp.  220-222. 


TEST  FOR  FORMALDEHYDE  535 

after  three  weeks  only  a  faint  trace  could  be  detected  in  a 
sample  of  1  part  in  25,000."i 

Butter  and  Oleomargarine. — Pure  butter  should  have 
good  taste,  odor,  and  color;  it  should  not  be  rancid,  and 
should  not  contain  too  much  water  or  salt,  nor  should  it 
have  any  added  coloring-matter.  The  average  composi- 
tion should  be  about  as  follows:  fat,  82  per  cent.;  casein, 
2  per  cent,  (riot  over  3  per  cent.);  ash  or  salts,  2  per 
cent.;  water,  13  per  cent.  Butter-fat  is  a  compound  of 
glycerin  wuth  certain  fatty  acids,  some  of  them  volatile 
and  soluble  in  hot  water,  others  non-volatile  and  insoluble 
in  hot  water. 

Oleomargarine  consists  of  ordinary  animal  or  vegetable- 
fats,  melted,  strained,  cooled  with  ice,  worked  up  with 
milk,  colored,  and  salted.  The  fats  are  usually  beef  or 
mutton-fat,  lard,  or  cotton-seed,  palm,  or  cocoanut  oil. 
If  care  and  cleanliness  are  observed  in  the  manufacture, 
oleomargarine  is  not  harmful  nor  innutritions,  but  it 
should  not  be  sold  as  butter. 

Fraud  is  to  be  detected  by  observing  the  difference 
in  composition  and  properties  of  the  fats.    For  instance: 

BUTTEB-FAT.  BeEF-FAT,    ETC. 

1.  The  specific  gravity  is  very  1,  Beef-fat,  etc.,  is  never  above 
rarely  below  910,  never  below  909.8.  904.5. 

2.  The  soluble,  volatile  fatty  2.  Rarely  more  than  0.5  percent., 
acids  average  between  6  and  7  per  never  above  0.75  per  cent. 

cent.,  never  below  4.5  per  cent. 

3.  The  insoluble  fatty  acids  form  3.  Generally  about  95  per  cent, 
about    88   per    cent,    of    the    total 

weight  of  butter  fat. 

4.  The  melting-point  of  the  fat  4.  Rarely,  if  ever,  above  82**  F. 
varies  from  86°  to  94°  F.;  is  usu- 
ally from  88°  to  90°  F. 

5.  Is  readily  and  completely  solu-  5.  Less  so,  and  leaves  a  residue, 
ble  in  ether. 

6.  Under  the  microscope  pure  6.  The  contours  of  the  small  oil 
butter-fat  consists  of  a  collection  of  globules  are  less  distinct,  and  the 
small  oil  globules,  with  an  occasional  larger  ones  are  more  numerous  and 
large  one.  irregular  in  size. 

7.  No  crystals,  except  when  the  7.  Crystals  of  the  non-volatile 
fat  has  been  melted.  acids  are  often  seen. 

^  Lefifmann  and  Bevan,  loc.  cit. 


536      EXAMINATION  OF  AIR,   WATER,  AND  FOOD 

To  determine  the  specific  gravity  of  butter-fat:  Melt 
a  quantity  of  the  butter  in  a  beaker  in  a  water-bath  at 
about  150°  F.  When  the  fat  is  perfectly  clear  and  trans- 
parent, carefully  decant  the  fat  from  the  lower  stratum 
of  water,  curd,  and  salt  into  a  fine  filter;  collect  the 
filtrate  and  pour  into  a  specific  gravity  bottle,  which  has 
been  previously  weighed,  both  when  empty  and  when 
filled  with  distilled  water  at  100°  F.  See  that  the  bottle 
is  exactly  full  of  the  fat,  wipe  clean,  and  weigh  when  the 
temperature  is  as  near  100°  F.  as  possible,  because  solidi- 
fication soon  begins  below  this  temperature.  Subtract  the 
weight  of  the  bottle,  divide  by  the  weight  of  the  water 
which  the  bottle  will  hold,  and  multiply  by  1000;  the 
result  is  the  specific  gravity. 

To  find  the  melting-point:  Pour  a  little  melted  fat  into 
a  small  test-tube  (2"  x  i'O  and  cool.  Partly  fill  two 
beakers  of  unequal  size  with  cold  water;  place  the  test- 
tube  in  the  smaller  (taking  care  to  allow  no  water  to  mix 
with  the  fat),  and  the  smaller  in  the  larger,  and  gently 
heat  the  outer  beaker.  Suspend  a  thermometer  in  the 
smaller,  near  the  test-tube,  and  note  the  temperature  when 
the  f Sit  begins  to  melt;  this  is  the  melting-point. 

To  determine  the  percentage  of  insoluble  (non-volatile) 
fatty  acids:  To  6  grammes  of  butter-fat  add  50  c.c.  of 
alcohol  containing  2  grammes  of  caustic  potash  (KHO) 
and  boil  gently  for  fifteen  or  twenty  minutes  to  saponify 
the  fat.  Dissolve  the  soaps  thus  formed  in  150  to  200  c.c. 
of  water,  and  decompose  with  about  25  c.c.  of  dilute 
hydrochloric  acid.  The  separated  fatty  acids  are  poured 
upon  a  weighed  filter-paper,  washed  with  2  liters  of 
boiling  water,  dried  at  95°  to  98°  C,  and  then  weighed. 
The  weight  of  these  insoluble  fatty  acids  should  not  be 
over  90  per  cent,  of  the  weight  of  the  butter  fat. 

Flour  and  Bread. — Wheat  Flour. — Characteristics: 
almost  perfectly  white,  smooth  and  free  from  grit;  no 
mouldy  or  unpleasant  odor;  cohesive  when  lightly  com- 
pressed; no  signs  of  parasites  under  the  microscope;  water 
less  than  18  per  cent.;  ash  less  than  2  per  cent. 


BUTTER,  FLOUR,   AND  BREAD  537 

"The  roller  process  yields  a  slightly  rough  flour,  and 
the  hard  winter  wheat  may  give  a  yellowish  tinge.  Good 
flour  is  slightly  acid  to  test-paper,  but  not  to  the  taste,  and 
an  acidity  that  may  be  recognized  by  the  senses  means  a 
change.  Acid  flour  means  sour  bread,  and  any  disagree- 
able taste  or  odor  indicates  bad  flour.  When  boiling 
water  is  poured  on  a  little  flour,  there  should  arise  no 
odor  but  that  of  freshly  ground  wheat."^ 

To  determine  the  percentage  of  water  and  ash:  In  a 
weighed  platinum  (or  porcelain)  dish  place  about-  50 
grammes  of  flour,  w^eigh,  and  dry  over  a  water-bath  for 
an  hour  or  so;  then  complete  the  evaporation  in  a  water- 
oven  until  there  is  no  further  loss  of  weight;  weigh,  sub- 
tract this  weight,  less  the  weight  of  the  dish,  from  the 
original  weight  of  the  flour.  Multiply  the  remainder  by 
100  and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  percentage  of  water.  Then  ignite  the  dried 
flour  in  the  dish  and  incinerate  until  there  are  no  longer 
any  black  particles  and  only  the  ash  remains;  cool,  weigh, 
subtract  weight  of  dish,  multiply  the  remainder  by  100, 
and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  percentage  of  ash. 

To  determine  the  percentage  of  gluten:  By  means  of  a 
glass  rod  mix  a  weighed  quantity  of  flour  with  a  little  dis- 
tilled water  into  a  stifle  dough;  then  repeatedly  wash  away 
the  starch  and  soluble  constituents,  kneading  the  dough 
with  the  rod  or  fingers,  and  continuing  until  the  wash- 
water  comes  away  clear;  the  gluten  and  a  small  amount 
of  fat  and  salt  remain.  Spread  on  a  weighed  dish  or 
crucible  lid,  dry  in  a  water-oven,  and  weigh;  multiply  by 
100  and  divide  by  the  original  weight  of  the  flour.  The 
result  is  the  approximate  percentage  of  gluten.  The  gluten 
should  pull  out  into  long  threads;  otherwise,  it  is  poor. 

"The  relative  strength  and  elasticity  of  the  gluten, 
which  are  determined  comparatively  by  manipulating  a 
small  quantity  of  flour  intimately  mixed  with  half  its 

*  Colonel  A.  A.  Woodhull,  M.D.,  article  on  "Military  Hygiene,"  in 
The  Reference  Hand-book  of  the  Medical  Sciences. 


538       EXAMINATION  OF  AIR,  WATER,  AND  FOOD 

weight  of  water,  make  a  standard  for  comparison.  This 
is  known  as  the  dough-test,  and  its  failure  shows  weak 
flour,  from  poor  wheat  or  imperfect  milHng  and  defective 
gluten."! 

An  excess  of  water  impairs  the  keeping  quality  and 
lessens  the  amount  of  nutriment  in  the  flour.  An  excess 
of  ash  indicates  the  addition  of  mineral  substances.  A 
deficiency  of  gluten  may  also  indicate  that  the  flour  is 
not  pure  wheat  flour.  Parasites  and  fungi  are  especially 
likely  to  be  found  in  old,  damp,  or  inferior  flour. 

To  test  for  mineral  substances:  Shake  a  little  flour  in  a 
test-tube  with  some  chloroform,  and  allow  it  to  stand  for 
a  few  minutes.  The  flour  floats  and  any  mineral  matter 
sinks  to  the  bottom,  when  it  can  be  removed  with  a 
pipette  and  examined  under  a  microscope. 

Wheat  Bread. — Characteristics:  fairly  dry,  light,  and 
spongy;  clean  and  nearly  white;  of  pleasant  taste;  not 
sodden,  acid,  or  musty;  ash  not  over  3  per  cent.;  no  para- 
sites or  mouldiness;  no  flour  other  than  wheat;  but  little, 
if  any,  alum;  no  copper  sulphate. 

Test  for  alum:  Add  5  c.c.  of  a  5  per  cent,  tincture  of 
logwood  and  5  c.c.  of  a  15  per  cent,  solution  of  ammonium 
carbonate  to  25  c.c.  of  water;  soak  a  crumb  of  the  bread 
in  this  for  a  few  minutes;  drain  and  gently  dry;  alum 
is  indicated  by  a  violet  or  lavender  color;  its  absence  by 
a  dirty  brown  color  on  drying. 

For  further  tests  and  details  in  work  pertaining  to  a  laboratory  of 
hygiene  the  reader  is  referred  to  Fox's  Examination  of  Food,  Air, 
and  Water;  Kenwood's  Hygienic  Laboratory;  Bergey's  Hand-book  of 
Practical  Hygiene;  Harrington's  Practical  Hygiene;  Leffmann  and 
Bevan's  Food  Analysis;  Standard  Methods  of  Water  Analysis  of  the 
American  Public  Health  Association;  Thresh's  Simple  Method  of  Water 
Analysis.  In  the  latter  the  author  has  devised  a  series  of  tests  requiring 
the  simplest  possible  apparatus  and  a  group  of  solid  reagents  which  can 
be  prepared  in  tabloid  form,  each  piece  containing  exactly  the  quantity 
required  for  the  respective  test.  The  entire  outfit,  which  can  be  had  of 
Burroughs,  Wellcome  &  Co.  or  their  agents,  can  be  packed  in  com- 
paratively small  space  and  is  easily  transported  from  place  to  place, 
thus  enabling  the  investigator  to  make  his  tests  at  or  near  the  source  of 
supply. 

1  Colonel  A.  A.  Woodhull,  M.D.,  loc.  cit. 


INDEX 


Absorption  of  foods,  240 
Accessory  foods,  251 
Acetylene  gas,  86 
Adulterants    and    preservatives, 

274 
Adulteration  of  foods,  274 
Aerobic  beds  for  sewage,  423 
Air,  69 

bacteria  in,  75 
collection  of,  510 

currents,  determination  of  ve- 
locity of,  111 
direction  of,  115 

diseases  caused  by  impure,  91 

distribution  of,  112,  117 

dust  in,  effect  of,  92 

examination  of,  509 

filtration  of,  108 

purification  of,  74 
by  fire,  131 

saturation  of,  80 
Air-propeller,  122 
Air-supply,  conduits  for,  107 

source  of,  107 

volume  of,  106 
Alcohol,  279 

indications  for  use  and  absten- 
tion, 280 

relation  of,  to  food,  280 

rules  governing  use  of,  282 

use  of,  in  sickness,  281 
Alexins,  57 
Altitude,  effect  of  change  in,  70, 

71 
Alum  in  bread,  test  for,  538 

use  of,  in  purifying  water,  187, 
194,  205 
Amboceptors,  Ehrlich's,  62 


Ammonia,  in  air,  74 

"albuminoid,"  in  water,  226 

"free,"  in  water,  226 
Amvlopsin,  action  of,  239 
Anderson's  process  for  purifying 

water,  188 
Anemometer,  112 
Annatto,  test  for,  in  milk,  533 
Antigens,  56 
Antimicrobin,  67 
Antiseptics,  339 
Antitoxins,  58 

methods  of  preparing,  63 

statistics  of  use  of,  66 

theory  of,  58 
Apparatus  for  lighting,  83 

for    steam    disinfecting,    343, 
344 
Aqueous  vapor,  73,  79 
Area  drained  by  wells,  162,  167 
Argon,  72 
Army  canteen,  491 

medical  officers,  duties  of,  457, 
492 

rations,  476 
Arsenic  f)oisoning,  risk  of,  452 
Artesian-water,  151,  164 
Artesian-wells,  164 
Artificial  ventilation,  108,  120 
Ashes,  389 
Ashley  biological  reduction  tank, 

433 
Aspiration,  110 
Atavism,  291 
Atmosphere,  69 

composition  of,  69 

impurities  in,  74 

of  mines,  90 

natural  purification  of,  74 

of  ships,  91 

•       (539) 


540 


INDEX 


Atmosphere  of  sick-rooms,  105 

weight  of,  69 
Atmospheric  contamination,   ex- 
tent of,  103 
index  of,  103 
Autogenetic  diseases,  causes  of,  32 


B 


Bacilli,  40 

Bacillus,  the  colon,  in  water,  224 

Backus  heater,  130 

Bacteria  in  air,  75 

atypical  forms  of,  39 

classification  of,  40 

collection  of,  in  air,  510 

definition  of,  37 

differentiation  of,  45 

discovery  of,  37 

as  an  index  of  purity  of  filtered 
water,  204 

involution  forms  of,  39 

isolation  of  different  species  of, 
41 

parasitic,  48 
in  sewer-gas,  87 

pathogenic,  48 

requirements  of,  37 

saprophytic,  47 
Bacterial  examination  of  air,  510 

of  water,  224 
Bacteriology,  36,  37 
Bacterioproteins,  56 
Barracks,    construction    and   ar- 
rangement of,  464 
Bathing,  300 

rules  for,  302 

sea,  301 

time  of,  302 
Baths,  cold,  301 

pubhc,  303 

Russian,  304 

Turkish,  303 

warm,  303 
Beans,  nutritive  value  of,  273 
Bedding,  disinfection  of,  362 
Beef,  264 

Beef -fat,  characteristics  of,  535 
Beef-tea  as  a  stimulant,  278 

whole,  recipe  for,  269 
Berkefeld  filter,  213,  219 


Beverages,  283 

carbon  dioxide  in,  284 
ice-water  as  a,  221 
sanitary   precautions    concern- 
ing, 284 

Bichloride  of  mercury  as  a  disin- 
fectant, 348 

Bile,  action  of,  239,  240 

Biological  action  in  soil,  158 

Blackboards,  school,  322 

BoiUng,  disinfection  by,  360 

Boric  acid,  test  for,  in  milk,  533 

Bread,  271 
test  for  alum  in,  538 

Broiling,  268 

Broths,  268 

Biichner,  humoral  theory  of,  57 

Burial  permits,  501 

Butter,  263 

examination  of,  535 

Butter-fat,  characteristics  of,  535 

Buttermilk,  257 


Calcium  hydrate,  351 

Calcium  hypochlorite  for  polluted 

water,  188,  476 
Camp  hospitals,  464,  486 
Camps  of  detention,  384 

diseases  of,  471 

disposal  of  excreta  in,  481 
of  garbage  in,  485 

important  points  regarding,  463 

infectious  diseases  in,  465 

latrines,  482 

location  of,  460 

pollution  of,  467 

of  probation,  384 

of  refuge,  385 

typhoid  fever  in,  466-469 

water-supply  of,  473 
Canteen,    army,    advantages   of, 

491 
Carbohydrates,  functions  of,  230, 
232,  245 

sources  of,  245 
Carbolic  acid  as  a  disinfectant, 

349,  369 
Carbon  dioxide,  72 
in  atmosphere,  73 


INDEX 


541 


Carl)on  dioxide  in  beverages,  284 
in  dwellings,  78 
effects  of,  77 
excretion  of,  78,  297 
normal  proportion  of,  73 
Pettenkofer's  test  for,  515 
poisoning  by,  96 
respiratory,  82 
in  soil-air,  89 
tests  for,  513 
monoxide  from  stoves,  129 

poisoning  by,  97 
proportion  of,   to  nitrogen  in 
diet,  243 
Carbonic   acid.     See  Carbon  di- 
oxide. 
Care  of  school-houses,  327 
Carpets,  etc.,  disinfection  of,  362 
Census,  the,  498 

reports,  U.  S.,  statistics  from, 
22-26 
Centralized  heating,  130 
Cereals,  269 
Cesspools,  dangers  of,  392 

disinfection  of,  391 
Cheese,  262 

Chemical  disinfectants,  347 
treatment  of  sewage,  418 
of  water,  185 
Child  labor,  443 
Chimneys,  use  of,  for  ventilation, 

118 
Chloride  of  zinc,  351 
Chlorides  in  water,  test  for,  518 
Chlorin,  188,  352 

or  chlorides  in  water,  226,  518 
test  for,  518 
Chlorinated  lime,  188,  347 

Eoda,  347 
Chromium  poisoning,  risk  of,  452 
Cistern  filter,  153 
Cisterns  for  rain-water,  150,  153 
Clark's     process     for     purifying 

water,  185 
Cloak-rooms     in     school-houses, 

325 
Closets,  earth-,  392 
pail-,  392 
water-,  405 
Clothing,  304 

advantages  of  woollen,  305 
conveyance  of  infection  by,  309 


Clothing,  disinfection  of,  362 
influence  of,  upon  health,  308 
materials  usckI  for,  305 
purpose  of,  304 
relative  absorption  of  heat  by, 

309 
of  soldiers,  480 
sophistication  of,  308 
tests  for  materials  for,  307 

Coal,  products  of  combustion  of, 
82 

Coal-gas,  composition  of,  98 
I      poisoning  by,  98 
j      products  of  combustion  of,  83 
;  Coffee,  278 

Cold  baths,  effects  of,  301 

Colony,  a  bacterial,  41 

Combustion  products,  82 

influence  upon  health,  96 
specific  gravity  of,  84 

Comparative  mortality  figure,506 

Condensed  rations,  478 

Condiments,  251 

Congenital  diseases,  291 

Consanguineous    marriages,    ob- 
jections to,  294 

Construction  and  care  of  wells,  166 
of  school-hou&es,  322 

Contact  beds  for  sewage,  423 

Contagion,  nature  of,  51 

Contagious  dise'ases,  definition  of, 
32 
in  schools,  329-335 
ophthalmia  in  schools,  334 

Contamination  of  atmosphere,  ex- 
tent of,  103 

Convected  heat,  125 

Cooking,  object  of,  241,  267 
thoroughness  of,  267 
of  vegetables,  273 

Copper  sulphate  in  water,  526 

Corn,  270 

Corrosive  sublimate  at  a  disin- 
fectant, 348 

Cotton  in  clothing,  306 

Cowls,  ventilating,  109 

** Cramps,"  cause  of,  when  bath- 
ing, 302 

Cream,  digestibility  of,  256 

Creolin,  349 

Cresols,  349 

"Crowd-poison,"  81 


542 


INDEX 


"Crowd-poison."  effects  of,  94 
Cubic  space  in  ventilation,  106 
Culture-media,  preparation  of,  44 

reaction  of,  41 

sterilization  of,  43 

temperature  of,  41 


Darnall  filter,  474 
Death-certificate,    standard,    503 
Death-rates,^  504 

d^ily  or  weekly,  504 

showing  sanitary  gain,  22 

standard,  506 

zymotic,  504 
Deep  water,  151,  164 

wells,  164 
Deficiency   diseases,    faulty   diet 
in,  252 
vitamines  in,  251 
Delousing    stations,    importance 

of,  481 
Deodorants,  339 
Detention  at  ports  of  entry,  375 

camps  of,  384 

period  of,  in  quarantine,  375, 
378 
Devices  for  ventilation,  113 
Dietetic  rules,  241 
Dietetic^,  233 

esthetic  factors  in,  233 
Differentiation  of  bacteria,  45        ' 
Diffusion,  108 

law  of,  70 

rate  of,  108 
Digestion,  gastric,  237 

hydrolysis  in,  235 

intestinal,  239 

physiology  of,  234 

sahvary,  236 
Digestive  ferments,  234 
Diphtheria  antitoxin,  method  of 

preparing,  63 
Direct  radiation,  140 
Direct-indirect  radiation,  141    ■ 
Diseases  affecting  animals  used 
for  food,  286 

bacterial,    immunotherapy   in, 
56 


Diseases,  classification  of,  31 

congenital,  288 

deficiency,  vitamines  in,  251 

definitions  of,  31 

and  causes  of  autogenetic,  32 

due  to  drinking-water,  173 
to  impure  air,  91 
to  respiratory  vitiation,  95 

endemic,  50 

epidemic,  50 

important,  of  war,  471 

incubation  periods  of.  331 

infectious,  in  schools,  329 

inherited,  291 

methods  of  combating,  291 

occupational,  439 

pandemic,  50 

specific,  50 

study  of,  494 

transmissible  by  heredity,  288 

zymotic,  50 
Disinfectant,  definition  of,  338 
Disinfectants,  application  of,  in 
quarantine  work,  381 

chemical,  347,  369 

comparative  table  of,  359 

gaseous,  352,  364 

mechanical,  342 

physical,  363 

physiological,  342 

thermal,  342 
Disinfecting    apparatus,     steam, 

343,  344 
Disinfection,  33,  338 

of  bedding,  362 

of  carpets,  etc.,  362 

of  cesspools,  391 

of  clothing,  361,  362 

by  dry  heat,  346 

efficacy  of,  341 

evidence  as  to,  341 

of  excreta,  348,  349,  360 

final,  of  rooms,  361 

by  fire,  342 

by  formaldehyde,  354 

by  hot  water,  345,  364 

of  infectious  cases,  360 

personal,  361 

of  rooms,  361 

Schering's  method  of,  356 

of  school-houses,  325 

of  sewage,  437 


INDEX 


543 


Disinfection  of  sick-room,  360 

of  spores,  342 

by  steam,  343,  364 

thoroughness  of,  341 

Trillat's  method  of,  355 

of  vessels  in  quarantine,  381 
Disinfector,  duties  of  a,  338 
Distillation  of  drinking-water,  208 
Distribution  of  air,  112,  115 
Domestic  purification  of  water, 

206 
Dress,  influence  of  improper,  308 
Drinking-water,    distillation    of, 
208 

examination  of,  222,  518 

infection  by,  173 

necessity  for  boiling,  217 
Drip-safes,  405 

Dry  heat,  disinfection  by,  346 
Duration  of  life,  mean,  507 
provable,  507 

of  school  work,  315 
Dust,  influence  of,  in  air,  92 
Duties  of  army  medical  officers, 

457,  492 
Duty  of  physicians,  27 


Earth-closets,  392 

peat  in,  use  of,  393 
Economy  in  heating,  126 
Eggs,  value  of,  as  a  food,  263 
Ehrlich's  lateral  chain  theory,  60 
Ejector  eewerage  system,  391 
Emscher  tank,  420 
Environment,  influence  of,  34 
on  predisposed  constitutions, 
291 
Enzymes,  action  of,  234 

characterifcticf  of,  235 

digestive,  234 

of  vegetable  origin,  242 
Epidemic,  definition  of,  50 
Estimation  of  radiating  surfaces, 

144 
Examination  of  air,  509 

of  butter,  535 

of  drinking-water,  222,  518 

of  flour,  536 

of  food,  527 


Examination  of  milk,  527 
Excreta,  disinfection  of,  348,  349, 
360 
disposal  of,  in  camps,  481 
Exercise,  295 

amount  necessary,  300 
effect  upon  brain  development, 
299 
upon  digestive  functions,  298 
upon  excretion,  298 
upon  heart  and  circulation, 

298 
upon  heat  production,  298 
upon  muscles,  296 
upon  respiratory  organs  and 
functions,  296 
importance  of,  295 
Exhaust  system,  121 
Exhaustion  theory  of  Pasteur,  57 
Expectant  attention,  danger  of, 

286 
Expectation  of  life,  507 
External  ventilation,  101 
Eye-strain,  317 


Factors  of  ventilation,  102 

Factory  sanitation,  445 

Fans,  ventilating,  121 

Farr,  Dr.  Wm.,  20 

Fatigue,  causes  of,  300 

Fats,    constructive   property   of, 
248 
digestibUity  of,  249 
functions  of,  230,  232,  247 
I)roperties  of  butter-  and  beef-, 

535 
sources  of,  247 

to   determine  specific   gravity 
of,  536 
melting-point  of  butter-,  536 

Fatty  acids,  to  determine  insol- 
uble or  non-volatile,  536 

Feeble-mindednesj ,   transmission 
of,  292,  293 

Ferments,  digestive,  234 

Ferrous  sulphate  in  mechanical 
filtration,  205 

FUter-beds,  plan  of,  192 

Filters,  action  of  sand-,  193 


544 


INDEX 


Filters,  cistern,  153 

cleansing  of  sand-,  202 

construction  of  sand-,  194 

Darnall,  474 

functions  of  sediment  layer  in, 
193 

hou&e,  212 

material  used  in  sand-,  196 

mechanical,  203 

percolating,  423 

preliminary,  202  ~ 

rough,  202 

sprinkling,  423 

trickling,  423 
Filtration,  190 

of  air,  108 

of  rain-water,  152 

rate  of,  201 

regulation  of,  195 

of  sewage,  424 
Fire,  disinfection  by,  342 
Fireplaces,  126 
Fish,  265 
Fixtures,  location  of  house-,  398 

traps  of  house-,  398 
Flies  as  carriers  of  infection,  467, 

478 
Floor  space  of  school-rooms,  324 

in  ventilation,  107 
Flour,  characteristics  of  wheat-, 
536  . 

test  for  minerals  in,  538 
to  determine  the  ash  in,  537 
gluten  in,  537 
water  in,  537 
Flues,  hot-air,  size  of,  136 
Flush  tank.  Field's  siphon,  413 
Food,  229 

amount  necessary  for  life  and 
health,  243 

cooking  of,  241 

definition  of,  229 

functions  of,  229 

inspection  of,  478 

of  the  soldier,  476 

tests  of,  527 
Food-principles,  classification  of, 
229 

functions  of,  232 

properties  of,  232 

use  of,  230 
Food-relationship  in  diet,  243 


Food-salts,  function  of,  232,  249 

sources  of,  250 
Foods,  absorption  of,  240 

accessory,  251 

adulteration  of,  274 

relative  value  of,  276 

use  of  preservatives  in,  275 
Forbes  sterilizer,  208 

advantages  of,  211 
Forces  of  ventilation,  108 
Formaldehyde,  354,  365 

as  a  deodorant,  359 

disinfection  by,  354 

methods  of  using,  355 

production  from  methyl  alco- 
hol, 357 

regenerators  for  vaporizing,  355 

solutions  of,  354 

test  for,  in  milk,  534 

with  permanganate  of  potash, 
358 
Formalin,  354,  369 
Formic  aldehyde,  354 
Formula  for  problems  in  ventila- 
tion, 106 
Free  pratique,  383 
Fruits,  274 
Frying,  269 
Fumigation,  352,  362 
Furnaces,  hot-air,  133 
Furs,  307 


Garbage,  disposal  of,  389 

in  camps,  485 
Gaseous  impurities,  76 
Gases,  poisonous,  of  occupations, 

452 
Gas-stoves  and  grates,  130 
Gastric  digestion,  237 
Germ  theory,  37,  49 

arguments  for,  50 
Germicides,  338 
Gluten,  to  determine  percentage 

of,  537 
Glycogen,  246 

Graphic  charts  of  statistics,  497 
Grate  fires,  open,  126 
Grates,  ventilating,  127 
!  Grease  trap,  401 


INDEX 


545 


Crirdirg  grain,  effect  of,  270 
Ground-water,  151,  167 

current  of,  160 

purification  of,  168 
Growth-promoting      substances, 

252,  257 


Haptopbores,  61 
Hard  water,  154 
Hardness  of  water,  154,  227 
permanent,  154 
temporary,  154 
tests  for,  625 
Headache  in  school-children,  317 
Health,  definition  of,  30 

of  soldiers,  455,  473 
Heat,  air-movement  due  to,  110 
convected,  125 
distribution  of,  134,  139 
radiant,  125 
relative  absorption  by  clothing, 

309 
transmission  of,  139 
Heating  by  hot  air,  133 
by  hot  water,  139 
by  steam,  140 
Heliotherapy,  311 
Heredity,  definition  of,  288 
importance  of  observing  laws 
of,  289 
Hippocrates,  hygienic  rules  of,  19 
Hospital  ships,  488 
tent,  the  Munson,  488,  490 
tents,  487,  490 
Hospitals,  impurity  of  air  in,  106 
military^  464,  486 
ventilation  of,  106 
Hot-air  flues,  shape  of,  136 
size  of,  136 
furnaces,  133 

air-supply  of,  136 
combustion  of  fuel  in,  137 
limitations  of,  139 
location  of,  134 
requirements  of,  134 
Hot  water,  disinfection  by,  346, 
364 
heating,  133,  139 
House-drainage,  394 
35 


House-drains,  396 
i  air  inlets  to,  397 
I  connection  of,  with  sewer, 

!  397 

j  with  soil-pipes,  397 

'  construction  of,  397 

House-filters,  212 
cautions  regarding,  212,  220 
classification  of,  213 
dangers  of,  212 
materials  for,  217 
requisites  of,  213 
House-fixtures,  connection  of,  to 

waste-pipes,  398 
House-quarantine,  386 
House-warmingj  124 
Human  exhalations,  efifects  of,  96 
Humidifier,  138 
Humidity,  excessive,  80 

relative,  determination  of,  510 
of  warmed  air,  137 
Humoral  theory,  67 
Hydrocarbon  lamps,  86 
Hydrocyanic  acia  as  an  insecti- 
cide, 353 
Hydrogen  dioxide  as  a  disinfec- 
tant, 351 
peroxide  as  a  disinfectant,  351 
sulphide,  symptoms  due  to  in- 
halation of,  98 
Hygiene,  ancient,  20 
definition  of,  17 
development  of,  as  a  science,  20 
industrial,  439 
military,  456 
naval,  492 
I     order  of  study  of,  26 
I      personal,  285 
!     progress  in,  21-26 
j     reasons  for  study  of,  27-29 
I     school,  314 

scope  of,  17-19 
'  Hygrodeik,  the,  512,  613 
Hygrometer,  use  of,  610 
Hypochlorites,  use  of,  to  purify 
water,  187 


Ice-water,  abuse  of,  221 
purity  of,  221 


546 


INDEX 


Illuminating  agents,  influence  of, 

83 
Illuminating-gas,  composition  of, 
98 
poisoning  by,  98 
Illumination,  apparatus  for,  85 

influence  of,  on  health,  84 
Imhoff  tank,  420 
Immunity,  theories  of,  57 
Immunotherapy,  62 

in  bacterial  diseases,  58 
Importance  of  dietetic  habits,  242 
Impure  air,  diseases  due  to,  91 

water,  diseases  due  to,  173 
Impurities  in  air,  74 

mortality  due  to,  93 
due  to  combustion,  82 

to  respiration,  etc.,  76 
gaseous,  76 
Impurity  of  air  in  hospitals,  105 
Incubation,  period  of,  53 

of  infectious  diseases,  330 
Index  of  atmospheric  contamina- 
tion, 103 
Indirect  radiation,  141 
Industrial  hygiene,  439 

fundamental  conditions  of,  441 
Infant  mortaUty,  causes  of,  505 

rate  of,  505 
Infection,  conditions  requisite  for, 
53 
conveyance  of,  by  clothing,  309 

by  oysters  and  clams,  266 
by  drinking-water,  174 
"droplet,"  94 
Infectious  diseases,  caufees  of,  32 
disinfection  of  cases  of,  360 
period  of  incubation  of,  53, 
330 
Inherited  diseases,  291 
Inland  quarantine,  384 
Inlets,  air,  to  house  drains,  397 
ventilation,  location  of,  116 
size  of,  117 
Inoculation,  50 

Inspection,  quarantine,  376,  383 
Intermittent  filtration  of  sewage, 

424 
Internal  ventilation,  102 
Intestinal  digestion,  239 
Involution-forms,    causation    of, 
39 


Iron,  effect  of,  in  water,  173 

sulphate,  205,  351 

test  for,  in  water,  526 
Irrigation  treatment  of  sewage, 

426 


Kefir,  257 

Kitchens,  camp,  care  of,  464 
in&pection  of,  478 

rolUng  field,  497 
Koch's  postulates,  52 
Koumiss,  257 
Kresols,  349 
Kuhn    formaldehyde    generator, 

358 


Labarraque's  solution,  347 
Lake-water,  157 

Lateral  chain  theory  of  immun- 
ity, 60 
Lead,  occupations  utiUzing,  449 

poisoning,  risk  of,  449 

test  for,  in  water,  520 

in  water,  174 
Leather,  307 
Leguminous   plants,   food   value 

of,  273 
Level  of  ground- water,  160 
Life-table,  factors  of,  507 

value  of,  507 
Light,  310 

germicidal  effect  of,  311,  342 

importance  of  an  abundance  of, 
312 

influence  of,  upon  health,  310 
upon  metabolism,  312 

penetration  of  sun-,  311 

therapeutic  effects  of  sun-,  311 
Lighting  agents,  influence  of,  83 

increased  by  prismatic  devices, 
313 

of  school-rooms,  322,  325 
Lime,  chloride  of,  as  a  dibinfec- 
tant,  347 

chlorinated,  as  a  disinfectant, 
347 

milk  of,  as  a  disinfectant,  351 
Linen  in  clothing,  306 


INDEX 


547 


Location  of  school-houseE,  325 
of  ventilation  inlets,  116 

outlets.  115 
of  Avells,  162,  167 

Loomis-Manning  filters,  215 

Lysins,  62 

Lyster  bag,  the,  476 


M 

Malaria  and  typhoid  fever,  468 
prevalence  of,   among  troops, 
471 

Marriage,  289 

proper  age  for,  289 

Marriages,  objections  to  consan- 
guineous, 294 

Mastication,  value  of,  237,  241 

Mean  after-lifetime,  507 
age  at  death,  507 
duration  of  life,  507 

Meat,  characteristics  of  good,  264 
composition  of,  264 

Meats,  cooking  of,  267 
digestibility  of  various,  265 
diseased,  266 
relation  of,  to  disease,  266 

Mechanical  filters,  203 

Medical  inspection  in  schools,  329 

Mercury,  bichloride  of,  as  a  dis- 
infectant, 348 
poisoning,  risk  of,  452 

Metchnikoff,  theory  of,  57 

Meters,  water,  148 

Micrococci,  varieties  of,  40 

Military  hospitals,  464,  486 
hygiene,  455 

importance  of,  456 
rations,  476 

Milk,  253 

care  and  preparation  of,  255 

as  a  cause  of  disease,  255,  258 

characteristics  of  good,  262,  527 

diseases  due  to,  258 

epidemics  due  to,  260 

of  lime,  351 

pasteurization  of,  255 

as  a  protective  food,  257 

scarlet  fever  due  to,  259 

as  a  source  of  infection,  258,  261 

test  for  annatto  in,  533 


!  Milk,  test  for  boric  acid  in,  533 
to  determine  the  ash  in,  529 
fats  in,  530 
total  soUds  in,  528 
for  formaldehyde  in,  534 
for  salicylic  acid  in,  533 
tuberculosis  and,  259 
typhoid  fever  due  to,  259 
use  of  preservatives  in,  262 
Milk-borne  epidemics,  character- 
istics of,  260 
Mines,  atmosphere  of,  90 
I  Moisture  in  warmed  air,  137 
I  Morbidity  of  wage  earners,  440 
I      rates,  506 

i  Mortahty,  cause  of  infant,  505 
I      due  to  impurities  in  air,  93 

rate  of  infant,  505 
j  Mortality-rate,  typhoid,  an  index 
!      of  water  purity,  177,  180 
Mortality-rates,  504 
;  Movement  of  heated  air,  1 10 
Munson  hospital  tent,  488 
Mutton.  265 


N 


Natural  ventilation,  108 
Naval  hygiene,  492 
!  Nervous  diseases  in  school-chil- 
i      dren,  315,  318 
Nessler's  reagent,  522 
New  York,  water  supply  of,  185 
Nitrates  test  for,  519 

in  water,  227 
Nitrification  of  organic  matters, 

47,  158 
Nitrites  tests  for,  521 
Schuyten's,  522 
in  water,  227 
Nitrogen,  72 

proportion    of,    to    carbon    in 
diet,  243 
Nuts,  274 


Oatmeal,  270 
Objections  to  stoves,  129 
Occupational  diseases,  439 
prophylaxis  of,  453 


548 


INDEX 


Occupational  morbidity,  440 
Occupations,     classification     of, 
446-448 

harmful  and  dangerous,  446 

poisonous  gases  of,  452 

utilizing  poisonous  metals,  449 
Oil-stoves,  131 
Oleomargarine,  535 
Open-air  schools,  326 
Ophthalmia,       contagious,       in 

schools,  334 
Opsonic  index,  59 
Opsonins,  59 
Organic  excretion,  81 

matters  in  water,  227 
Outlets,  location  of  ventilation, 

115 
Overwork,  effects  of,  in  school, 

315 
Oxygen,  71 

absorption  of,  78,  297 

tension,  effect  of  reduced,  71 
Oysters,  infection  by,  and  clams, 

266 


Pail-closets,  392 

Pancreatic  digestion,  239 
juice,  239 

Paraform,  354 

Paraformaldehyde,  354 

Parasites,    transmission    of,    by 
water,  177 

Parasitic  bacteria,  48 

Parasitology,  36 

Pasteur  filter,  214 

Pasteurization,  255    • 

Pathogenic  bacteria,  48 

Peat,    use    of,    in    earth-closets, 
393 

Pepsin,  action  of,  238 

Percolating  filters,  423 

Percolation      of      ground-water, 
158,  160 

Perflation,  110 

Period  of  incubation,  53,  330 

Permissible  impurity  in  air,  103 
in  soil,  159 

Peroxide  of  hydrogen  as  a  disin- 
fectant, 351 


Personal  disinfection,  361 

hygiene,  285 
Petri  dish,  43 
Pettenkofer's  test    for    carbonic 

acid,  515 
Phagocytosis,  theory  of,  57 
Phosphates  in  water,  227 

test  for,  527 
Phosphorous  poisoning,   risk  of, 

451 
Physical  examination  of  water, 
222,  518 

exercise,  effects  of,  293 

training,  aim  of,  299 
Physiology  of  digestion,  234 
Playgrounds,  328 
Plenum  system,  121 
Plumbing  for  sewage,  394 
Pneumatic  sewerage  system,  390 
Pneumonia,  infectiousness  of,  26 
Poisonous  gases  of  occupations, 
452 

metals,    occupations   utiHzing, 
449 
Pollution  of  well-water,  162,  167 
Population,  actual  increment  of, 
498 

daily,  504 

estimation  of,  499 

natural  increment  of,  498 

weekly,  504 
Pork,  2d5 

Portable  steam  radiator,  130 
Post  hospitals,  486 
Postulates  of  Koch,  52 
Precautions  in  sick-room,  360 
Predisposing  conditions,  34 
Preparation  of  culture-media,  44 
Preservatives,    adulterants    and, 
274 

in  milk,  262 

use  of,  in  foods,  275 
Prismatic      devices,       increased 

Ughting  by,  313 
Probable  duration  of  life,  507 
Probation,  camps  of,  384 
Products  of  combustion,  82 
Prophylactic  infection,  67 

intoxication,  67 
Prophylaxis,  33 

continuous,  necessity  for,  25 
I      of  occupational  diseases,  453 


INDEX 


549 


Protection  bv  vaccination,  386 
Proteid  food,  functions  of,  230, 
232,  244 
sources  of,  245 
Protozoa  as  a  cause  of  disease,  55 
Psychronieter,  the,  510,  511 
Ptomains,  49 
Ptyalin,  action  of,  236 
Public  baths,  303 
Pumping,  effect  of  excessive,  on 
quality  of  water  in  wells,  162, 
164 
Pure  food  and  drugs  act,  provi- 
sions of,  274 
Purification  of  air  by  fire,  131 
of  atmosphere,  74 
of  ground- water,  158 
of  river-water,  155 
of  sewage,  416 

of  subsoil-  or  ground-water,  158 
of  water,  178 

by  chemical  treatment,  185 
domestic,  206 
by  filtration,  189 
by  subsidence,  182 


Quarantine,  370 

at     Canadian    and     Mexican 

ports,  383 
conditions  requiring,  375 
history  of,  370 
house,  386 
inland,  384 
laws,  purpose  of,  371 
local,  386 
origin  of,  370 
original  meaning  of,  370 
railroad,  385 

regulations  at  ports  of  depart- 
ure, 372 
of  entry,  374 
during  voyage,  374 
school,  330-334 
stations,  location  of,  376 

requisites  for,  377 
treatment    of    passengers    in, 
378 
of  vessels  in,  380,  381 
Quarantines,  inspection  of,  376, 
383 


Radiant  heat,  125 

Radiating  surface,  estimation  of, 

144 
Radiation,  direct,  140 

direct-indirect,  141 

indirect,  141 
Railroad  quarantine,  385 
Rainfall,    amount  of,    per    acre, 

152 
Rain-water,  151 

cisterns,  150,  153 

conductors,  trapping  of,  398 

filtration  of,  152 

softness  of,  154 

storage  of,  153 
Rations,  army,  476 
Raw   vegetables,    typhoid   fever 

and,  273 
Receptors,  Ehrlich's,  61 
Recruits,  age  of,  457 

examination  of,  456 

habits  of,  460 

qualifications  of,  456 

rejection  of,  causes  for,  454 
Refuge,  camps  of,  385 
Registers,  size  and  locations  of, 

136 
Registration  area,  24 

records,  importance  of,  501 
Rejection  of  unfit  recruits,  26 
Relation     of     water-supply     to 

typhoid  fever,  176 
Relative    size    of     school-rooms, 
324 

value  of  foods,  276 
Removal  of  sewage,  390 
Rennin,  238 

Reservoirs,  purification  in,  182 
Respiration  impurities,  effect  of, 

77 
Respiratory    vitiation,     diseases 

due  to,  95 
Retention  theory  of  Chauveau, 

57 
River-water,  154 

self-purification  of,  155 
Roasting  and  broiling,  268 
Rooms,  final  disinfection  of,  361 
Rubber,  use  of,  as  a  protective, 

307 


550 


INDEX 


Salicylates,   test  for,   in  milk, 

533 
Salicylic  acid,  test  for,  in  milk, 

533 
Saliva,  functions.of,  236 
Salivary  digestion,  237 
Salts,  food-,  functions  of,  232,  249 

sources  of,  250 
Sand  ejectors,  202 
filters,  192-204 
separators,  203 
Sanitarians,  need  for,  29 
Sanitary  cordon,  384 
Sanitation,  33 
factory,  445 

improved,  results  due  to,  21-24 
value  of,  21 
Saprophytes,  functions  of,  47 
Schering's  lamps,  355 

method  of  disinfection,  356 
Schizomycetes,  36 
School    children,     eye-strain    in 
317 
headache  in,  317 
nervous  diseases  in,  315,  318 
physical  defects  of,  319,  335 
prevention    of    infection    of 

329 
spinal  deformities  in,  319 
teeth  of,  336 
vaccination  of,  334 
furniture,  arrangement  of,  321 
influence  of,  on  health,  319 
hygiene,  314 
infirmaries,  332 
pathology,  314 
quarantine,  330-334 
rooms,  dimensions  of,  324 
Ughting  of,  322,  325 
relative  size  of,  324 
work,  duration  of,  315 
School-houses,  care  of,  327 
cloak-rooms  in,  325 
construction  of,  322 
disinfection  of,  325 
lighting  of,  322,  325 
location  of,  325 
ventilation  of,  322 
warming  of,  322 
water-supply  of,  326 


Schools,   contagious  diseases  in, 
329-334 
medical  inspection  of,  329,  335 
open-air,  326 
Sea-bathing,  301 
Seats,  arrangement  of,  in  schools, 

321 
Sedimentation,  182 
Self-study,  importance  of,  286 
Septicemia,  definition  of,  54 
''Septic-tank"  system  of  sewage 
treatment,  418 
advantages  of,  418,  421 
Sewage,  changes  in,  416,  421 
composition  of,  390 
disinfection  of,  437 
disposal  of,  415 
filtration  of,  424 

intermittent,  424 
pail  system  of  removal  of,  392 
purification  of,  416 
removal  of,  390 

methods  of,  391 
treatment  of,  by  biological  re- 
duction tank,  419,  433 
by  chemicals,  417 
by  electricity,  437 
by  irrigation,  426 
by  sedimentation,  417 
by    the    "septic-tank"    sys- 
tem, 418 
by  straining,  417 
by  sub-irrigation,  426 
ultimate  disposal  of,  415 
water-carriage  of,  390,  411 
Sewage-plumbing,  394 
requirements  of,  394 
Sewage-pollution  of  water,  155 
Sewage-traps,  399  (see  Traps) 
Sewerage,  ejector  system  of,  391 
pneumatic  system  of,  390 
Shone  system  of,  391 
Sewer-gas,  87 
bacteria  in,  87 
composition  of,  87 
influence  of,  on  health,  99 
Sewers,  411 

advantages  of  "combined,"  412 
shape  of,  411 
of  "separate,"  413 
construction  of,  411 
"separate,"  413 


INDEX 


551 


Sewers,  "separate,"  specification 
for,  414 

ventilation  of,  412,  414 
Shallo^v  wells,  161 
Shoes,  influence  of  improper,  309 
Shone  sewerage  system,  391 
Sick-rates,  506 
Sick-room,  care  of,  360 

disinfection  of,  361 

impurity  of  air  in,  105 

precautions  in,  360 

screening  of,  360 
Silk  in  clothing,  306 
Siphonage  of  sewer  traps,  401 
Size  of  ventilation  inlets,  117 
Skimmed  milk,  257 
Smead  system  of  ventilation,  1 16, 

323 
Soda,  chlorinated,  347 
Soil,  88 

limit   of  permissible  impurity 
in,  159 

purifying  action  of,  158 
Soil-air,  87 

bacteria  in,  90 

circulation  of,  89 

composition  of,  89 

influence  of,  on  health,  99 
Soil-pipe,  395 

connection     of,     with    house- 
drain,  397 

location  and  construction  of, 
395 

testing  of,  403 

ventilation  of,  395,  397 
Soldier,  clothing  of,  479 

food  of,  476 

instruction  of,  in  hygiene,  486 

work  of,  491 
Soldiers,  weights  carried  by,  481 
SoUds,  total,  in  water,  225 
Soups  and  broths,  268 
Source  of  air-supply,  107 
Sources  of  water-supply,  149 
Specific  diseases,  50 
Spinal  deformities  in  school-chil- 
dren, 319 
Spirilla,  40 
Spores,  characteristics  of,  39 

formation  of,  38 
Springs,  151,  160 
Spring- water,  160,  165 


!  Spring-water,  purity  of,  160 

I  Sprinkling  filters,  423 

I  Statistical  inquiry,  principles  of. 

I      495 

I  Statistics  showing  sanitary  gain, 

21-24 
Steam,  disinfection  by,  3.43,  364 
j  Steam-heating,  140 
Steapsin,  action  of,  240 
Sterilization  of  apparatus,  43 

fractional,  43 

mechanical,  342 

methods  of,  43 

of  water  by  boiling,  206 
Sterilized  milk,  255 
Sterilizer,  Forbes's,  208 
Sterilizers,  44,  207 
Stills,  208 
Stimulants,  277 

cautions  in  use  of,  281 

classification  of,  277 

function  of,  277 

indications  for  use  of,  277 
Stoves,  128 

gas-,  130 

gases  from,  129 

objections  to,  129 

oil-,  131 

ventilating,  128 
Studies  in  school,  order  of,  316 
Subirrigation,  426 
Subsidence,  water  purification  by  , 

182 
\  Subsoil-water,  151,  157 
Sullage  water,  disposal  of,  485 
Sulphate  of  iron,  351 
Sulphur  dioxide,  352,  364 

fumigation  with,  353 
Sulphuretted  hydrogen,  98 
Sulphurous  acid  gas,  98,  352 
Surface-water,  151,  154 


Tea,  278 

and  coffee,  abuse  of,  278 
Tents,  crowding  in,  461 

hospital,  489,  490 
Tests  of  well-water,  168 
Theory  of  antitoxins,  58 

of  Biichner,  57 


552 


INDEX 


Theory  of  Chauveau,  57 
of  Ehrlich,  60 
germ,  48 

of  Metchnikoff,  57 
of  opsonins,  59 
of  Pasteur,  57 
of  phagocytosis,  57 
of  Wright,  59 
Total  soHds  in  water,  225 
Toxalbumins,  48 
Toxemia,  definition  of,  54 
Toxins,  48,  58 

Training,  physical,  aim  of,  299 
Transmission  of  heat,  139 
Trap,  bell,  400 
grease,  401 

McClellan's  antisiphoning,  402 
S  or  siphon,  400 
Traps,  399 
seal  of,  399 
siphoning  of,  401 
vent-pipes  for,  401 
Trickling  filters,  423 
Tricresol,  350 
Trillat's  method  of  disinfection, 

355 
Trypsin,  action  of,  240 
Tuberculin,  use  of,  258 
Tuberculosis  and  milk,  259 

constructive  value  of  fat  in,  248 
due  to  school-life,  319 
effect  of  dust  in  causing,  93 

of  pure  air  in,  79 
influence  of  heredity  on,  292 

of  sunlight  on,  311 
as  an  occupational  disease,  452 
recrudescence  of,  319 
reduction  in  mortality-rate  of, 
24  25 
Turkish  bath,  303 
Typhoid   fever   as   an   index   of 
water  purity,  177 
in  camps,  466-469,  473 
death-rates  in  cities,  171 
dissemination  of,  466-469 
due  to  flies,  467 
to  milk,  259 

to  oysters  and  clams,  266 
epidemics  of,  176 
incubation    period    of,    466, 

469 
inoculation  against,  469,  473 


Typhoid  fever,  malaria  and,  468 
raw  vegetables  and,  273 
in  rural  populations,  169 

Tyrotoxicon,  258 


Vaccination  of  school-children, 
334 

protection  by,  386 

statistics,  386-388 
Variety   in   food,    necessity   for, 

233 
Vegetables,  272 

cooking  of,  273 

typhoid  fever  and  raw,  273 
Velocity   of   air-currents,    deter- 
mination of.  111 
Venereal  diseases,  control  of,  492 
Ventilating  apparatus,  113 

grates,  127 

stoves,  128 
Ventilation,  artificial,  108 

definition  of,  102 

devices  for,  113 

extent  of,  necessary,  104 

external,  101 

of  factories,  453 

factors  in,  102 

fans,  121 

forces  of,  108 

heating  and,  101 

inlets,  location  of,  116 

internal,  102 

natural,  108 

plenum  system  of,  121 

practical  points  in,  123 

problems,  formula  for,  106 

of  school-houses,  322 

of  sewers,  412,  414 

Smead  system  of,  1 16,  323 

of  soil-pipes,  395,  399 

of  vent-pipes,  401 

of  water-closets,  410 
Ventilators,  109,  113 
Vessels,  entry  of,  375 

treatment  of  infected,  370 
Vigor,  conditions    for    maintain- 
ing, 244 
Vital  resistance,  value  of,  33 


INDEX 


553 


Vital  statistics,  494  j 

grouping  in,  496  | 

influence  of,  24  ! 

methods  of  obtaining,  498      1 
numerical  standard  in,  496     i 

units  in,  495 
of  occupations,   caution  re-  ; 

garding,  441  \ 

probable  error  in,  497 
recent,  22-24 
value  of,  495 

of  series  in,  497 
variation  in,  497 
Vitamines,  230,  251 

in  deficiency  diseases,  251 


W 

Warmed  air,  humidity  of,  137 
Warming  of  school-houses,  322 
Waste-pipes,  395 

connection    of,    to    house-fix- 
tures,  398 
with  soil-pipes,  402 
Water,  146 

ammonia  in,  226,  522 

bacterial  examination  of,   224 

boiling  of,  206,  217 

bottle  for  collecting  samples  of, 
519 

chemical  examination  of,   225 
treatment  of,  185 

chlorin  in,  226,  518 

classification  of,  170,  228 

collection  of,  for  analysis,  224 

cost  of  sickness  due  to  polluted, 
180 

deep-  or  artesian-,  151,  164 

diseases  caused  by  impurities 
in,  173 

double  supply  of,  148 

effects  of  impure,  177 

examination  of,  22,  518 

excretion  of,  297 

filtration  of,  190 

ground-  or  subsoil-,  151,  157 

hardness  of,  154,  227,  525 

lake-,  157 

lead  in,  174,  526 

level  of  subsoil-,  160 

meters,  148 


Water,  nitrates  in,  227,  519 
nitrites  in,  227,  521 
organic  matters  in,  227 
percolation  of,  158,  160 
phosphates  in,  227,  527 
physical  examination  of,  222, 

518 
purification  of,  155,  158,  178 

in  household,  206 
purity  of  subsoil-,  161 
quantity  of,  necessary,  146 
rain,  151 
river-,  154 

sewage-pollution  of,  155,  162 
sources  of,  149 
spring-,  160,  165 

purity  of,  161,  165 
sterilizer  for  schools,  207 
storage  of,  182 
subsoil,  157 
supply  of  camps,  473 

of  New  York  City,  185 

of  schools,  326 

typhoid  fever  and,  169 
surface-,  151,  154 
tests  for  physical  properties  of, 

222,  518 
total  sohds  in,  225 
transmission   of   infection   by, 
174 

of  parasites  by,  177 
Water-carriage  of  sewage,  394 
Water-closets,  405 

connection  of,  to  water-supply, 

410 
hopper,  408 
location  of,  410 
pan,  406 

plug  or  plunger,  407 
requisites  for,  405 
siphon,  409 
valve,  406 
ventilation  of,  410 
washout,  408 
Water-puritv,  index  of,  177,  180 
Water-supply  of  camps,  474 
of  cities,  147,  171 
infection  of,  176 
relation  of,  to  typhoid  fever, 

169,  171,  179 
of  school-houses,  326 
Weights  carried  by  soldiers,  481 


554 


INDEX 


Well-water,  pollution  of,  161,  167 

testing  of,  168 
Wells,  area  drained  by,  162,  168 

construction  and  care  of,   166 

deep  or  artesian,  164 

location  of,  162,  167 

shallow,  161 
Welsbach  light,  85 
Wheat,  270 

bread,  characteristics  of,  538 

flour,  270 

characteristics  of,  536 


Winds  as  ventilating  agents,  109 

Women,  labor  of,  443 

Woollen  clothing,  advantages  of, 

305 
Wright,  opsonic  theory  of,  59 


Zinc   chloride  as  a  disinfectant, 

351 
Zooglea,  40 
Zymotic  diseases,  50 


lO  35  67 


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